Help! My boyfriend wants to get married but its too soon...?

My boyfriend is 19 and i'm 18. We've been dating a year and a half and I feel we are very much in love. He's recently been talking about getting engaged (we wouldn't get married of course until I was at least 20) thats fine with me, but I also feel extremely pressured. I love my boyfriend very much but i'm going to be a freshman in college in August and I just don't think I want to go into college already engaged. In fact last night I asked him if we could take a break for a little once i'm in college to date other people and experiment before we decide to make such a huge commitment, so that I could know for sure I wouldn't have any regrets. He of course took it the wrong way and accused me of wanting to be with other guys and not loving him. So am I wrong for wanting to date a little more to make sure we are supposed to be together, or should I "just already know" that he is the one.