Thank you for sharing what you are carrying. The tension at home, the arguments, and the distress you describe in your emotions, mind, and even your body are heavy, and it is understandable that you long for healing and peace.
Scripture makes clear that the most important peace is first vertical before it can be horizontal. Your relationship with God is the center upon which every other relationship turns. When that center is right, it begins to bring order to your relationship with family, with others, and with your own heart. When it is not right, every other relationship feels out of balance, no matter how hard you try to fix one part while the rest pulls apart. For that reason the first question to bring before the Lord is not only how to calm the conflict at home, but whether you have peace with God through forgiveness in Jesus Christ.
God offers that peace freely. He extends peace to those who are near and to those who have wandered far, calling to each one to come and be healed and forgiven. Through the blood of Jesus, atonement has been made so that you can have communion with God, not as a legal burden where you try to earn His favor, but as a loving relationship where you are forgiven and accepted by faith. That loving relationship changes what you want. You no longer want what displeases Him because you love Him and want to please Him. That is where real and lasting peace begins. The Bible also warns that there is no settled peace for those who continue in rebellion against God, who remain like a troubled sea. But when you turn to Christ and receive His forgiveness, the war is over. You are no longer running from God or fighting against Him, and He gives a peace that passes understanding to guard your heart and mind.
From that place, God then teaches you how to pursue peace with others. The wisdom that comes from above is peaceable, and those who sow peace reap a harvest of righteousness. Jesus said blessed are the peacemakers. That does not mean peace at any cost, or pretending that wrong is right, but it does mean not returning evil for evil or insult for insult, being compassionate and courteous, and as far as it depends on you, living peaceably with all people and actively seeking and pursuing peace.
In your situation this has several practical implications. Your relationship with your girlfriend should be examined in the light of God's design. Scripture presents marriage as a lifelong covenant between one man and one woman and as a beautiful picture of the relationship between Christ and His church. Sex and living together belong within that covenant, not outside it. God has not called His people to trial arrangements that test compatibility through cohabitation or physical intimacy before marriage. If you are to marry, you do not sin, but you are called to pursue that relationship in purity, self control, and honor, seeking counsel and walking in a way that does not become a stumbling block to others. Ask the Lord to show you whether this relationship is leading you both closer to Him and toward a holy marriage, or whether it is pulling you away from obedience.
At the same time, you are called to honor your parents. That does not mean you must obey an ungodly command, but it does mean you treat your mother with respect and gentleness even when you feel she is treating you rudely. Constant arguing sows strife and deepens wounds. It is better to sow peace through calm words, listening, prayer, and patience, trusting God to work in her heart as well as your own. There is a close connection between the health of your soul and the health of your mind and body. When your mind is stayed on the Lord and you trust in Him, He keeps you in perfect peace, and that inner peace often brings relief to the mental and physical strain that conflict creates. Jesus said, Peace I leave with you, my peace I give to you, not as the world gives. That is the peace you need most right now.
So my prayer for you is not simply that circumstances become easier, but that each person involved would seek first peace with God. I pray that you would know the forgiveness and healing that comes through faith in Jesus Christ, that your mind would be stayed on Him and kept in perfect peace, and that out of that loving relationship with God you would be given wisdom from above to act in purity, humility, and love. I pray that God would soften hearts in your family, that arguments would give way to courteous and compassionate conversation, and that you and your girlfriend and your parents would each seek the Lord's will above your own desires. May the Lord grant you grace, mercy, and peace as you walk in truth and love, and may He guide your steps toward whatever honors Him most, whether that leads toward marriage in His timing and His way, or toward a different path that keeps you faithful to Him.
If you have not already, bring these matters honestly before the Lord, ask Him to search your heart, and seek wise, godly counsel from mature believers who can walk with you personally and help you apply Scripture faithfully to your decisions.
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. 
