My two cents
I had my first seriously relationship when I was 13 years old. He was 15 at the time, so the two year age difference seems pretty normal to me I guess. The relationship lasted about 4 months and by serious I do mean that it got, some what, physical. I don't think that it emotionally scared me but I do think it set me up for a life of "wanting" to be in a relationship and not feeling normal being single.
I think that you are capable of feeling love and strong feelings at any age.. so legalities aside, go with what feels right for you and for her - don't let bullies talk you down for caring about someone.