When should i break up with my boyfriend.?

We've been dating for almost 3 months . I told him from the get go i was a virgin and wanted to wait. not till marriage cause im not like the religious type, but ya know wait until i was emotionally and physcially ready for the consequences of my actions. and what could happen since this is a baby making proccess. (sex). BC and Condoms are never 100% effective and i'd rather not take that risk and end up being a statistic and one of the 10% that DO get preganant I dont want a child until im in well into my late 20's. so that is when i will be particpating in sexual activities. I'm 19 now, almost 20. My boyfriend is 24. He said he will wait for me whenever im ready. but its gonna be a while before im ready and i highly doubt he will wait all these years. Hell he might not even wait one year. And i cant have him cheating on me, or breaking up with me first. i want to be the one to break up with him. not the other way around. We make out a lot and i defintely DO find him sexually attractive. but i have self control unlike the thousands of other teeny boppers out here, and can refrain myself from doing the dirty deeed. so if we were to be completely alone in a bedroom we probably wouldnt have sex cause i have that much self control.. None of my relationships last longer than 2 months anyways, so i doubt we will even be together in a year.. or years.. but anyways, should i wait a few months before breaking up with him, or do it soon?