Prenatals are fine. As a matter of fact, my doctor recommended I take them before I was even trying to get pregnant to "keep my eggs healthy" as he put it. It's also good to start them even before you start trying so that when you do get pregnant, you will already be taking the right vitamins.View Thread
If you were pregnant, it would be too early for symptoms as it takes 6-10 days for a fertilized egg (if there is one) to implant. Occasionally, a woman will ovulate right before or during her period but it's rare. I think your sore breasts are due to hormones.
Also, if your boyfriend did not urinate after ejaculation and before putting his penis in your vagina, there was still semen in his urethra that could cause pregnancy.
If you do not want to become pregnant, be sure to at least use a condom every time.View Thread
You may have not ovulated and no ovulation usually means no period. It's common, especially in teens, and most women will have it happen to them at least once during their reproductive years.View Thread