Hello,
Missing two pills and the use of antibiotics can affect the efficacy of the pills. If you miss your periods then you can test 1 week- 10 days after you miss your periods or you can test for pregnancy by a highly sensitive pregnancy test 10 days post ovulation with a sensitive ( 20 - 25 mIU ) pregnancy test. Also I would suggest you to get your serum HCG levels estimated since this is more specific than urine for pregnancy tests. The HCG (it is a hormone) levels rise only in pregnancy and its presence will confirm the status of your pregnancy.
I hope it helps. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Well, antibiotics can affect how the pill works. If you are two weeks into taking them, then you havn't missed a period yet. I would use a backup method of contraception for now and give the doctor a call and ask if you should stop the pill for the rest of the cycle and use another form of contraception or continue on with backup contraception.