My boyfriend and I have been dating for a bit more than two months. Two weeks after we started dating, he got tested for STDS and he came up clean. Around two and a half weeks ago he and I had sex and he used a condom the whole time. Two days later, I thought I had started my period and used a tampon, except I found out it was brown and wasnt heavy. After that, it stopped for two days. One morning, 5 days after having had sex, I noticed a small amount of brown spots in my underwear, however, it had already stopped. Today, 17 days after having sex, the brown spots started again, only a minuscule amount more than before, which I believe to be coincidence. I have not had any other symptoms with the exception of mood swings, which is somewhat normal because I'm an emotional teenager. My friend mentioned about knowing someone who went through a similar situation but wasn't pregnant.
Could I be pregnant, or is this a normal symptom after first time sex?