Condom busted on a high fertility day but I use to be on birth control, but I stopped, now I have a period every other month could I get pregnant?

Absolutely Yes. Anytime you have unprotected sex near (and before) you ovulate you're taking a chance on getting pregnant. Odds on conceiving are dependent on frequency of sex for you and ejaculates for your partner. Average couples will conceive about 85% of the time in a 12 month time period. Your statistical odds are about 7%...Safe sex every time!
Absolutely. Though unlikely if you are regularly irregular. If you have menses every 60 days consistently, then you typically ovulate 60 minus 14 (typical length of post-ovulatory phase)= day 46. But never count on this as your body can always ovulate when you least expect it!