25+ days late... Help?!

So I was due for my period on thanksgiving, it's not after Christmas and I still haven't gotten a period. I stopped taking BC in August but we use the pull out method. (We're not trying but also VERY okay if we get pregnant) since I've been late I've taken two pregnancy tests (both first pees of the day) and both have come out negative. Since I stopped BC, I've gotten a period every 26-28 days... I'm at a loss on what's going on because I continue to get cramps like my periods coming every few days since thanksgiving but no period and my nipples hurt. HELP!