Okay I Had Unprotected Sex With A Friend Who Is

Okay I had unprotected sex with a friend who is taking birth control but she doesn't take it at the same time everyday and an hour after 1 hour after having sex, she took "Plan B" (one step & one pill) and she had spotting like ten hours later. She was supposed to have her period 4 days after but it's been 6 days and she hasn't gotten it, and she says it burns when she pees, do you think she might be pregnant?