God wants you to try your best to be pure, but he is very aware of how difficult this is. Our ultimate goal should be to control our passions and only use them in the way God intended. Our God given sexual capacity is meant for marriage… not our amusement. The fact that you struggle with this tells me you are on the right path!
The best advice I can give you is to avoid bad television shows, music and pornography like the plague! While an occasional wet dream or act of masturbation is almost unaviodable, WHAT YOU LOOK AT AND LISTEN TO… IS WITHIN YOUR CONTROL! Pray every day for God’s protection from these things.
Your goal should be daily prayer and PROGRESS toward purity. When you fall to sin, make it a point to go to confession as reasonably soon as you can. Pray for God to send into your life, when the time is proper, a good and pure minded wife for you to share the gift of sexuality with!
For now, just concentrate on doing the very best you can and trust in God’s mercy to forgive you when you slip!