Can i get pregnant while i'm on the pill i missed one pill and taking antibiotics had sex with pre cum 8 days before my period?

Yes: Even under ideal circumstances, the pill is not 100% effective. Combine that with missed dose, antibiotics, and known exposure to semen, the only way to be sure is to do an appropriately timed pregnancy test.

Risk: Some antibiotics can impact effectiveness of oral contraception. If otherwise taken religiously, missing one oral contraceptive pill is not likely significantly change efficacy. Pre-ejaculate may contain large amounts of viable sperm (less common), smaller amounts of sperm that are dead or alive or no sperm. Thus, there is potential for pregnancy with pre-ejaculate. Sperm need to be deposited