Wow, you seem a lot like me when it comes to the depression stuff. I would go off birth control, but I have to take a primary and secondary form in order to take Accutane.
Anyway, I wish you the best. As I'm sure you know, there is no real way to ensure that you won't get pregnant. Use condoms, like you said, and maybe spermicide to go along with. The best thing I've heard to do is try low-dose hormone birth control (Nuvaring) if you need the protection. Unfortunately, even if you know you don't want children, most doctors will not allow tubal ligations or complete sterilisation unless you're over a certain age (I've heard 30+ years old) or if you have at least one child.
Tell us all if getting off birth control works!
PS: What are you taking for birth control?
PPS: Maybe also try talking to a psychologist or doctor during your birth control hiatus. This same advice was recommended to me in my latest thread in Tilted Sexuality.