Hi. Im 16 Years Old, I Am Sexually Active. Me

Hi. Im 16 years old, i am sexually active. Me and my boyfriend had sex probably two weeks ago, he came in me, and then we had sex probably about 7 times 4-5 days ago, and he came in me about 12 times he said. My last period was on the 10th of this month, and today i went to the bathroom, and noticed brownish, red kind of not really, on my underwear and when i wiped. Could i be pregnant?