What's the chance that I'm pregnant?

Izabel • Swimming and Art
I really just want to know if it's possible that I could be pregnant or if I should be worried. 
So I started Birth Control at the start of April of 2017.
I never missed a pill, only taken one or two later from the first pack, and so forth.
Well I got my second pack, and I took the pills on time every single day, well on May 3rd my boyfriend (now ex) and I had sex, the conform broke and he came in me. 
 At the time I didn't worry too much because it seemed unlikely. 
Well now it's been three weeks since the incident, and my period is "late" by two days.
However, I had spotting today but it was brown. And there doesn't seem to be any "tissue" or clumps and I don't seem to actually have a flow.
****Also, normally when I PMS I break out really bad. But I didn't break out at all this month. Could that be a sign?"****