There's no guarantee that the first person you get married to will be your soul mate forever. If, I'm not mistaken, 50% of married couples divorce. I have no source as I heard it about a year through the radio. Anyways, I'm not sure what your views on divorce are but it's safe to say most people see it as a common practice. At the end of the day, saving yourself until after marriage is pointless. Sex is a natural thing, the more fuzz you created around it, its practices and when God thinks it's the right time to do it only creates more curiosity in young lovers. All that needs to be said is that you need to have protection every single time. And the masturbation thing is just stupid. Are we just suppose to ignore our natural urges? Those are the kind of people who end up raping. You can do as you like, but the waiting thing is unnecessary in this day in age. We aren't little kids asking what our wee-wees and hoo-has are for anymore.
Also, demi and selena are the worst examples imaginable. They will end up like britney and rihanna in a few years. You are listening to Disney radio way too much buddy.