It may and it may not. It sounds like it probably is because he's getting hormonal injections and now has more testosterone to throw around (punny??)
Use a condom until you get on the pill. Or a Lea's shield, or a female condom, or spermicide jelly. Seriously, you're playing with fire. Have him use a condom. I've heard the "feel" is not worth the baby and all the hassles and problems that come with that. Please, please, please use a condom or something until you get on BC because if there is more of a chance that you'll get pregnant now and we just went through great lengths to affirm that you're
not ready yet.
I would definitely bug your mom about trying a different birth control, but in the meantime, use a condom. Also, you
need to tell your doctor that you're sexually active, and also visit a gynecologist for regular tests, even if you have one partner only. It's part of the responsibilities that come with leading a healthy sex life!!
Sorry if I'm like, hassling you, but I think these are things you need to do right now and I believe that very, very strongly.
PM me if you want additional support about convincing your boyfriend, ok? I'm here.