Am I pregnant ?? Please help! Advice please?

I had sex and the condom broke, *** got inside me
The next afternoon, I GOT MY PERIOD
WHILE on my period I bought plan b (I split the pill itself in half I took one half and then the OTHER half 45min later)
Now my period is supposed to come in 3 days and my boobs hurt, like they ALWAYS do before I get my period.
I dance A LOT 3 nights a week and I havn't noticed any cramps or nausea at all
Could I still be pregnant ? PLEASE HELP