No period, fear of infertility - is it even possible?

I have always had an inconsistent period. Multiple times it will not come for months at a time. Then it goes from like 80 days to 15 and then 45. Eventually I got on the pill and was able to have normal periods for three years while taking it. I stopped taking it in October and have not had a period since. Recently we had a mishap and I had to take plan B, but the concern remains... should I even be worried? Does me not having my period mean I am completely infertile? Would love to hear of success stories of people having same situation and kids being possible. Any comment or advice helps.