if i'm pregnant will the depo shot cause harm to my baby?

Hi,
Welcome to ehealthforum,
The symptoms that you describe could suggest possibility of pregnancy. The antibiotic use can also affect the efficacy of your hormonal contraceptive. The chances of pregnancy are possible if you had been sexually active without additional protection. Wait and watch for your periods/withdrawal bleeding. If pregnancy is suspected, or if you miss your periods, or if you have abnormal periods, consider visiting your doctor/gynecologist at the earliest for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). Consider being in regular monitoring and follow-up with your treating doctor/gynecologist and report any new/abnormal symptoms immediately.
Take care.