Ouch, depo is just wrong. That stuff can fuck up a body more than AAS can.
Anyway, I think the BC would interfere with her gains using AAS. Also, I'd be careful of anti-e's or you could have a little surprise. Personally, I'd say get off the birth control before taking AAS. Hell, I don't think any women should be on birth control anyway. Progestins can screw her up for the rest of her life. Say goodbye to her libido too.