Is infertility hereditary?

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Hey guys, so honestly I've never had a need to be worried about this, but now that I am engaged to a loving man who wants kids sooner than later, I'm getting worried. We are not trying, we have been using condoms and birth control. But I'm 20 years old now and I've had an irregular period since I was 11. What happens in a few years when my fiancé and I are married and want to try for a baby? I'm scared about not being fertile. My mom and my sister also have irregular periods, I'm not sure why, we are all really healthy and active. My mom said that her and my died tried for years and years to have a baby, they where even in the process of adoption. She says getting pregnant was a miracle because she didn't think it would ever happen. If me and my sis also have the same symptoms as our mom (being irregular) should I be worried? I don't see why I should see a doctor about it yet because obviously I don't want a baby yet, but it's something that kinda haunts me:( any advice?