Worried

I've been with my partner for 10 years this year, for the last 4 years I've gone off the pill and we never used protection and nothing has happened, ever. I'm so irregular, my period is so painful, I miss it sometimes and other times it's 3 weeks late! For a few months it was ok and regular & this month I was 10 days late and really thought I might be pregnant but I woke up yesterday and was so upset, not pregnant again! I'm worried there's something wrong with me! So depressing