You are launching out on your own as an independent official "adult". There are several significant life transitions during this time that can sometimes seem overwhelming even though good.
Temptations to compromise sexually are out there all the time, such as the seemingly practical and logical opportunity to travel alone with your boy-/girlfriend. Keep your eye on the ultimate "prize" - God's vision for marriage - so that you can keep yourself pure and exercise appropriate boundaries in relationships.
If you're exploring a committed relationship in marriage, it is advisable to discuss your sexual histories earlier rather than later as there are far-reaching implications on your relationship. Regardless, we have a redemptive God who can help you overcome any kind of unhealthy habit (eg, masturbation, pornography) and start anew.