Can’t get pregnant again

Hi ladies, I hope y’all are good. So I have a question and please no being rude. So I have two little girls, 4 and 7, with my ex who I was with since 8th grade till two years ago. I’m currently in a new really happy, healthy relationship for a while now. So, I’m not trying to get pregnant just curious. We don’t use protection at all and he doesn’t pull out but I haven’t once gotten pregnant with him. We said if it happens, then we’ll be happy but not trying to. My question is with me having irregular periods and being stressed about other life stuff, do you think that’s why I haven’t gotten pregnant or maybe now I’m infertile? I want to know because someday I will love to have a child with him and need to know if I should get checked out and stuff. Please be nice. I’m 25 btw.