Should I be worried?

Last Saturday my boyfriend and I had unprotected sex and well he pulled out but the day after I bled. The second day after we had sex I bled again in the morning and I got scared so I took the plan b pill that day. And ever since then I still continue to bleed a little in the mornings and sometimes in the afternoon. Does this mean that I'm pregnant? Or are those just side effects of the pill? I'm very nervous and I don't know if I should be worried or not.