Am I pregnant ?

I had unprotected sex 4 weeks ago. He didn’t cum. there was just precum. He wasn’t all the way in me .I’m not on birth control but I took 10 orsythia birth control pills as a morning after contraceptive and then my period started the day it was supposed to but it was only 4 days. Really heavy the first 2 then light and then non existent the rest. My periods normally last 5-6 days. I’ve been having headaches and lower back pain and a little bloated. Am I pregnant or could it be symptoms from the birth control or from ovulating ?