Confused about possible relationship due to obsticle

Hey,
I'm 16 years old, 17 in October (2007) and I'm sure that whilst reading my post, a lot of people will disagree with me - but that's fine, that's why I'm here.

I met a girl last year (it was through a primary school), when I was 15, and almost from the time I first saw her, I fell in love with her. It's because of this, I have no idea what to do. Besides the fact that I've been single all my life and never really thought about relationships and things, she was only 11 years old (now 12, and 13 in 2008). There is roughly 4 years and 4/5 months between us.

I have known her father and sister for ages as they are neighbours, and her sister was in the same school as me (just 2 years older), but we weren't really friendly - we just knew each other. Other families aren't really close, but they're friendly and talk often. Within the last year I have gotten to know her mother (who still doesn't really know me), and her younger brother.

What I'm trying to say is, our families are friendly, but there is an age gap which knocks everything out and confuses me to hell. I honestly have no idea what to do.

What would you do? If your a parent yourself, how would you react?

Thanks
G.V.

Thanks! I really do appreciate your help and opinion.
I understand what you mean about age gaps as there are 12 years between my grandparents. I am in the UK not the USA, which as far as I know, there are no laws against things like this. The only thing which would be illegal is sexual intercourse (which is 16+). This also means that she has started secondary school (= high school), but, I've just finished.

Thanks anyway, its really given me a good sight to what others (from people older than me) think of this situation.

Thank-you very much