I've been on birth control now for six days. I've never missed a pill and I've been taking them at the same time every day. I am getting a very wide variety of answers when it comes to asking when exactly the pill is at its full effectiveness. I'm getting anywhere between three days to three months. I'm taking Yaz if it makes any difference. Had unprotected sex this morning, and he did finish in me. Should I take the Plan B pill or will my birth control be effective against preventing possible pregnancy? And if I should take the Plan B, will it cause the same premature bleeding as it did the first time I took it (while not on birth control)? I'm not due for my period for another three weeks, and I don't want to risk throwing the cycle off, but if it's worth the risk, I will.

Thank you. Please any incite would be wonderful.