First Time, Might Be Pregnant, Scared

I'm 15, and I had my first time 3 days ago, and it was unprotected, really dumb of me, I know.

He didn't ejaculate and he wasn't in very long, but I know there is a slim chance that I still could be, (precum and whatnot)

Just now I saw I was bleeding, and I know that it could be a sign of pregnancy but honestly I'm not sure of it's that or if my period is very early, since I never really had spotting before.

I still talk with him, and if I am really pregnant I don't know how to tell him, or even if that I'm worried I'm pregnant. I'm planning to take plan b tomorrow since that's when I can get it, but if I do get pregnant there is no way I can keep it, I'm going to have to abort it, but I'm scared of my mom knowing, and how he'll feel about it, IF I even tell him

Need advice, and yes, again, it was a really stupid decision I know