TTC with irregular periods

Until last month I went a few months without getting a period (and wasn't pregnant). They've always been irregular, but when getting pregnant with my 1st wasn't really an issue I'd say. My 1st wasn't planned and I was only dating his dad a month and I got pregnant the 2nd time we had sex. Well now I'm married. Been married 2 yrs next month. In the past we weren't planning to get pregnant, but also weren't preventing it either. We've had unprotected sex 100's of times without me getting pregnant. Well now we are ttc and I'm worried bc my periods are so irregular that we're going to have a hard time. We both have kids from previous relationship so it's not like there's any big issues. Any advice for ladies who also have this issue?