Could I be Pregnant?

HI this is my situation..... I don't have periods like a normal female infact i rarely have them at all. I have POS and i have been having nausea and headahces for over amonth now, I am a big woman but this is the first time in my life i have felt to fatigued all the time. I do plan on going to the doctor. I am on birth control but i was recently on antibiotics. I am really nervouse and to those who have read my prev. question you know why. I really don't want to be not right now. Either way i would love my child but I didn't want to have to do it alone. Can someone give me an aswer with out being cynical.