How long TTC with irregular periods?

I’m about a year postpartum and slowing down on breastfeeding, but still do not have regular periods back. We’ve started “not preventing” as I’m in my late 30s and would like another soon.

How do I count how long I’ve been TTC when deciding to see my OB? I know I’m supposed to go if it’s been 6 months, but that may not be 6 cycles since my periods are irregular.