Is this considered penatration? How at risk am I of becoming pregnant?

My boyfriend and I were "fooling around" and here's what happened:
I got on top of him and I just moved my underwear aside, and he just had his boxers on. I tried to get his penis in as deep as I could. But, it never came out of his boxers, and he never ejaculated. However, we were doing it for a while and I got very wet, and he probably leaked a little. It didn't go REALLY far in, but I did feel it in quite a bit. I'm 17, and he's 18. We've been together for almost 2 years now... we are going to spend the rest of our lives together so please no "You're still young." (Also, neither of us have been with another person sexually, and our family has no history of HIV {like breast milk type thing} so we don't have any STDs.)

I also am just at the end of my period (there's still blood but not much at all.) so how does that affect it? I've been looking around on the internet for some answers but I can't get a clear one.

Yes, I know condoms and birth control are amazing things, we have used them before. It was just something that happened.

I'm not too worried about it... I mostly just want to know the risk (yes I know there is one, I am wondering how much of one.)

Thanks in advance. :-)