Am I pregnant?

So, the last day of my period 8/16/16, my boyfriend and I had sex in the morning on his bed and he came inside me. Then the following day, we had sex in the shower again and he came inside me too. Last night we had sex and he didn't cum inside me but he's pretty damn huge and I was riding him...after we finished I cleaned myself down there and didn't see anything different. This morning I woke up and I have light brown discharge, and I'm wondering if it's dry blood from the end of my period or from riding him or if I could be pregnant?