late period?

I have been up to as far as 12 days late before but that was last January . My last period was January 20th and it is now February 24th. My boyfriend and I had sex about 5-6 times in January but wore protection every time (yeah I know anything can happen tho) but I'm also on BC but I never took the pill regularly in January , I skipped a few and was late a few bc of life things. I also took plan b in January cus of a mishap and still got my period . I am now 4 days late .. no craps, no nausea, my breast feel fine, I feel fine. I started taking my pill regularly everyday this past Sunday at the same time so I'm trying to figure out if it's my body adjusting or whaaat? Someone please give me tips :(