Unless you meant that you have suspicions she's pregnant but not being honest? I'm totally making assumptions, forgive me!
Sounds like you need a new girlfriend, then. Sorry to be so blunt! And I know it has nothing to do with your question. But if you can't trust someone you shouldn't be in a relationship with them.
Yeah, I'm not sure if antibiotics affect Depo either. Most likely they do, though.
I am trying to rule out any suspicions? I do have doubts about her and if possible i would like to verify.
The pill is effected by antibiotics, but i am not sure depo is effected.
Antibiotics usually counteract birth controls.
Don't know about any test to "verify" Depo has been taken. If you have a girlfriend and she claims to have had the shot, Depo is still not 100% effective at preventing pregnancy on its own. And it definitely doesn't protect against STDs.