Help plz?!

So I have irregular cycles and I got off BC to try to conceive about 4 months ago and had a pretty much regular periods after stopping BC but I all of a sudden didn't have a period last month and all pregnany test were negative still haven't had a period since August 29th. I had the same problem last year and a few years now skipping a few months or so then all of a sudden have a period idk what could be the problem!! Has anybody have any insight or opinions on this or what could be the problem. ?!! And has anybody conceived with this certain problem?!!!