OK, so um seriously going to date myself gere ,but...to think of what I was like when I was 19 to my today( I'm a few months shy of 29). Its a night and day difference. Now that's just myself. It would be incredibly ignorant of me to tell you anything about your relationship because I don't know you or your boyfriend. Honestly, you might just want to have a serious Convo with your bf to see what he has to say, then you dont have to be iffy about anything. Also, don't try and change for anyone. If your not ready for whatever he is then that's just the way it is. Be young, dont grow up to fast. Hope this helped:)
Age is just a number but it seems like the two of you are at different points in life. Things could work out for you though, if you really care about each other and you want it to work, it will. Don't listen to what other people say/think.
I am way too sassy to change, haha!