Has anyone been referred to a fertility doctor to see why you don’t have periods? And or why pregnancy isn’t happening?

Back story:

When I was in high school (I’m 32 now) I only had periods every 6 months (so 2 a year). Then when I got on birth control I never got it. I got off birth control almost a year ago and I had a period September and November of 2021 and that’s it’s. So super irregular periods kinda my whole life.

I would definitely like to know why I’m irregular or no periods at all and to see why I haven’t gotten pregnant again. I really want a 3rd baby.

Is it worth to go and just find out? or should I not worry about it and not have a 3rd one?