Anxiety in a relationship

Hey guys,

So I have a problem with anxiety and I have a pretty bad problem with over thinking things. i am in a perfect relationship with a great guy, at 16 this is my first relationship, I started dating him when I was 15 and I had no fears, our relationship started off so fast we exchanged i love yous without even being two months in, and I had not known him half a year before dating him, now we have been dating half a year and this month for the first time I've had some doubt's, i can't really explain what they are, we are literally perfect and we have talked about how we plan on being together for the rest of our lives, he is a mature person, and is graduating this week, and I always thought I was mature, but I am wondering if this was just to fast for me, I am planning on talking to him, I just want some other opinions on what I could be worried about, he is great he never pushes me into anything, we are planning on waiting until we are married, we agreed on that, we like each others families, and we haven't even gotten into a fight yet. I love him so much and it makes me sick to think of not being with him anymore, but i just need some other peoples thoughts. also exactly a month ago I had some similar thoughts, and that makes me think its is some kind of hormonal thing that triggars my worring. If you think I should slow down or do something to help my hormones, please tell me what would help in the comments. I dont really want any comments that try to make this post seem unimportant, it is VERY important to me and I would really appreciate anyone's help, thanks