Took plan b, I had a period then no period and tender breasts.

So I had unprotected sex, my bf however did not cum inside me but precumed instead. I took plan b two days after that. I then got my period 2 weeks after that as planned. It was heavy with bad cramps, it lasted for about 2 days, then I started getting a less heavy period that lasted around 3-5 more days. Its been 3 weeks since my last period. A month and a week since the intercourse, I haven't taken a pregnancy test. Now I feel bloated and have been burping non stop since I took plan b. It was my first time taking it. I had a brown discharge around a week ago one in one day and another the day after that. I also have really bad tender nipples. They hurt really bad. Please help, can I be pregnant? Or is it a hormonal imbalance?