I dated a 15 year old?

As an adult, yes there are laws against such, but if teenagers are together in school and having a relationship, I find this a very gray area, and not one that should be of concern. The line does have to be drawn somewhere, and is in the law. However, you are both school age, and in my opinion, you are not a "pedophile". There is a clear difference between a true pedophile (typically a creepy old man) and a 15 year old and 18 year old. You are growing up and have moved on. Stop worrying.