possibility of being pregnant??

Okay, so I usually don't post or ask questions like this, but my mind is driving me crazy going around and around about possibilities. A little background info, I have an 11 month old that I breastfeed and I stopped birth control when she was 5 months because it limited my milk supply. In order to avoid pregnancy I track my cycles, bbt, cervical mucus to the best of my ability. I am 12 or so days into my cycle, and my period this cycle was lighter than it normally is and was more spotting than anything. It lasted about 6 days and then on day 8 of my cycle my boyfriend decided not to pull out and I wasn't expecting it. Now I know how it works with ovulating and the cervix having to be open to get pregnant. If I'm wrong about any of this feel free to correct me! Anyways my question is, if he came in me, and none of it came back out on cycle day 8, and I'm pretty sure I'm ovulating or about to right now on day 12, is there a real chance that I could get pregnant with him not pulling out before I ovulate? ( I do know that there is always a chance of getting pregnant)  Sorry for such a lengthy post! Thanks for any help in advance!