When I was 14, I started dating a 17yo for a couple of years. My parents were also suspicious, but he talked them around and it the end they found him trustworthy. And for what it's worth, it was me leading him astray and not the other way around. Unlike what Michelle mentions, I was hardly innocence and a child-like body LOL. I was hormones out of control!
I don't see much wrong with it as long as you're not pushing her for a sexual relationship.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.