The two pill version of Plan B instructs the user to take 1 pill within 72 hours of unprotected sex and the second pill 12 hours later. Since both pills are identical (levonorgestrel 0.75 mg), it doesn’t matter which one you take first. If you took the second pill 17 hours after the first pill, it should still be effective. In addition, you state that you are on birth control as well which, if taken correctly, is effective at preventing pregnancy.
If you don’t have any withdrawal bleeding at the end of your birth control cycle, you should consider taking a pregnancy test.
