help!

I am 17 and I have been on the pill for about a year and having sex with my boyfriend for about the same time. The past month we had sex with a condom and then like an hour or so later without but we didn't finish because his mom got home. Another time about a month ago we had sex and he used a condom until the very end, he pulled out and the cum was no where near me. These are the only times we have had sex recently. I got my period a few weeks ago but it was very light and I'm now thinking it could be implantation bleeding. The only reason I think this is I have been very tired the past few days so tired my parents took me too the doctor. Do you think I could be pregnant? My boyfriend thinks maybe the time we had it an hour apart there could have been some left on the head? I am pretty good about taking my pill everyday but I didn't know it had to be at the exact same time so it's always a few hours of difference until about a week ago when I made an alarm. Help me please!