Could I be pregnant?

So recently me and my bf had sex and I usually don’t use condoms since I’m on the pill but recently I’ve been forgetting to take the pill since I started a new pack. I haven’t had sex since forgetting the pill and about 3 days after we were intimate I got my period like normal but after my period I’ve been feeling off. I’ve been getting very consistent headaches (not too bad) and light spotting after a week of my period being over. So I guess my question is would it be possible for me to be pregnant even thought I had my period 3 days after having sex? I know it’s impossible to get a period while pregnant but considering it was 3 days after does that even count as getting a period while pregnant?