What do you think about the situation I am in with my boyfriend?

I'm a 16 year old teenager girl that's going to high school. My boyfriend is a 18 year old going into college. We've been dating for 2 months. I really like him & I like to take things slow. Therefore, he wants me to show more affection since I really don't show a lot of it, & I'll admit it.. I don't. He's the one that shows the most affection while I like having more of a emotional relationship. Here's the fear I'm going through: He's going into college. He has so much more freedom than I do. He's becoming more mature for the real world. & I'm just a girl in high school that needs to stay focused as so does he. I fear that he may like another girl and get bored with me because I won't show a lot of "intense" affection. What I mean by that is, his hormones are racing like crazy & I don't want to be the girl that gives in to having , I just can't.You may question me why I can't have . I'm standing my own grounds and saying "no" because I have big dreams for my future. I need to stay focused. But seriously, the thing is that.. if I don't end up showing him more affection, it's just human nature for him to like someone else. I don't want him to leave me, I really like him but I'm not getting into full detail with the internet on why I like him, I'm just displaying the whole "affection" problem I have going on here. Please do not judge what I'm asking harshly. I would really appreciate it if I could get back some decent feedback.