I have been on yasmin (drospirenone and ethinyl estradiol) for 3 months and had unprotected sex yesterday.i took the pill after it but started antibiotics that day could i be pregnant?

Maybe not, but...: Sometimes, it can be hard to tell if a woman is in early pregnancy. For the rest of the birth control pill package, she can add condoms to help prevent pregnancy. After the month, she can do a urine pregnancy test if she is worried about pregnancy, or if she is is having unexpected spotting or changes in her menstrual bleeding.