Was on depo for 9 mo then switched over to bc for a few mo. then stopped bc and didn't get period for 5 mo, so i got back on bc. concerned??

Amenorrhea: you can get no periods or irregular periods fro deep shot please make sure you are not pregnant. get a pap smear

Not concerned: Not a real reason for concern. If you were having your period while on BC and stopped BC and didn't have periods, you may just need the BC to continue to have regular periods. Not uncommon in women in your age group especially if they are very athletic, have a low body mass index

No: No, your body has been bombarded with some hard core exogenous hormones (hormones from outside the body) in addition to the ones made in your body, so this has likely suppressed your ovaries in making your own hormones, thus the no period once you got off the Depo and the BC (your body was used to the ones from the outside). Your body needs time to readjust before having a normal period again.