plan B

So I'm 22 and I don't mind if I become a mother right now or not because I can provide for my child. So my bf and I had sex last night (5/10/17) and he came inside of me which he has never done without me being on birth control and I took a plan B pill and a few hours later I'm spotting very lightly. I haven't had a period for 2 months. May will make it 3 I've been to the doctor and waiting for results. I guess my question is, what is the bleeding from? I didn't rip or wasn't hurting.