You have poured out a heart that is very heavy and very weary, and it is right that you have brought it into the light rather than bearing it alone. To ask, do I get to heaven if I commit suicide, is to ask about life and death and eternity itself, and it must be answered with both truth and tender care.
Know first that your life is not your own to take. It is the gift of God, and He has set His hand upon it for a purpose. To destroy it would be a grievous sin against the Lord who made you, and we must not presume upon His mercy by choosing that path. Heaven is not entered by our endurance or by our despair, but by salvation through Jesus Christ alone, through His blood shed on Calvary and His rising from the dead. There is no other name by which we are saved. If you belong to Christ by faith, you are kept by Him, yet the way of faith is to cling to Him in life, to cry to Him in darkness, and to trust Him to carry you through, not to run from Him by your own hand. If you are thinking of taking your life, I plead with you not to remain alone with these thoughts. Seek help at once from a faithful pastor, a trusted Christian brother, a doctor or counselor who honors God, and tell someone near you of the depth of this darkness so they may walk with you and watch with you.
You speak of ADHD and OCD and PTSD, of depression and of singleness that feels like a bitter loneliness, and of years of praying that seem unanswered. Sometimes the child of God endures loneliness arising from the absence of godly society, and from the weight of infirmities that others cannot see. Our Savior Himself knew this loneliness. His cry, My God, My God, why have You forsaken Me, shows that He entered into the very feeling of being forsaken, though He was without sin. He knows what it is to feel that God is absent, and He has not despised that cry. That lament was an address to God, not against Him. He still said, My God, My God, and made a double effort to draw near. If God seems to have left you, or you think so, do not give up prayer. Pray as your Lord did and be more earnest than ever. Do not give up your faith in Him, but cry again and again, My God, My God. The words of God's Book, made living to you by the Spirit, shall be to your mind as angels, and God Himself shall have fellowship with you. If you cannot find your way into the heart of any truth of God, the Spirit of God has the clue to it, so ask Him to guide you into it.
You ask where is God, is He even real. The question comes from long pain and doubt, and doubt itself must be repented of, for unbelief in its heart denies His goodness. Yet God has not left Himself without witness. Jesus Christ, the Son of God, died on Calvary and was buried and the third day He rose from the dead and ascended into Heaven where He sits at the right hand of God. He reveals God to us, and His word is true because it glorifies God and not man. Why has God appointed a Sabbath day if He does not mean to give rest to men, and why does He send ministers to preach His Gospel unless He means to save men by the message He has given them to deliver. He is the faithful and true Witness, the very Word of God. If you can but believe in God, He will never desert you. If you can dare to trust Him, God will do. If you can trust, God will never allow you to be confounded, world without end.
You also speak of singleness and of regret that you once kept yourself as a virgin, and of following counsel to go to brothels where it is legal, and you say you do not regret it. I must speak to you plainly and lovingly here, for your soul's sake. What you were first given, to keep your body pure, was not a cause for regret but a good gift before God. Sex belongs within the lifelong covenant of marriage between one man and one woman, and outside of that it is sin, however the law of the land may permit it or a therapist may advise it. That counsel was not wise nor kind to your soul, and to follow it was to turn aside from God's way. Do not be deceived by what the world praises, for that religion which the world praises is often that which God abhors. There is forgiveness for this as for all sin, but it is found only in repentance and faith toward Christ. Repent of ever having disbelieved the Son of God, repent of having distrusted the blood of Jesus Christ, and turn to Him who justifies. It is God that justifies. Who is he that condemns. It is Christ that died, yes rather, that is risen again, who is even at the right hand of God, who also makes intercession for us. He can cleanse and restore and teach you His statutes.
Your desire now for a serious and faithful relationship is itself a good desire, for marriage is honorable and God Himself ordained it. Seek it not in the way of regret for purity, but in the way of holiness, asking the Lord to prepare you and to provide according to His wisdom, whether He leads you to marriage or calls you to serve Him in singleness for a season. In either case He can use you. He is the God of the hills and the God of the valleys, the God of the great and the God of the lowly, and He is present in both the stormy life of the afflicted and the quiet life of the contented. He sees you in your early years of adulthood and knows the number of your days and the weight you carry.
Therefore do not run contrary to the truth by doubting God. You are content to be in just such a place as God would put you, and yet your straits seem too many for you. Now is the time to exercise faith upon a living God. Your God is not worth having if He cannot help you when you want help. He recognizes you everywhere, He has created every worm that crawls and painted every flower that blooms, and the whole world is full of God to him who believes in Him. He hears when you declare your ways to Him, and He answers, Teach me Your statutes.
Cast yourself then upon Christ today. Confess your sin and your doubt and your need to Him. Ask Him to forgive you for seeking comfort outside His way, and to wash you in His blood. Ask Him to be your life and your hope, to lift the cloud of depression with His presence and with the help of those He has provided for body and mind. Seek a church where the Word is preached and where you may have heavenly company, for there God is pleased to dwell. Open His Book daily, even when feeling is absent, and speak honestly to Him as Father. And if the thought of suicide presses again, go at once to a brother in Christ, to a pastor, to a physician, and let them bear the burden with you.
The Lord increase your faith, and preserve you without spot until the day of His appearing. May He show you that He has not forsaken you, but has drawn near in Christ, and may He give you grace to trust Him one day at a time.
Prayer Focus: God, Thank You for loving me. Thank You for loving me, Jesus. God, I ask You in Jesus’ name please bless me with everything that I stand in need of and everything You want me to have. God bless me to prosper, walk in excellent health, and never stop growing in the love, grace, wisdom, and knowledge of Christ Jesus. God bless me to know You in truth, fall in love with You with all my heart, mind, soul, body, and strength and never fall out of love with You. God, bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, Your righteousness, and to always respect and obey You. Bless me to know You, the way You want me to know You. So that I will trust You with my life and anyway that You move in my life. Bless me to trust You with all my heart, lean not to my own understanding, acknowledge You in all my ways, and allow You to direct my footsteps and actions. Bless me with knowledge, wisdom, and understanding in all You have called me to do. 
