TTC while BF

I’m almost 11 months pp. I’m still breastfeeding my daughter, but have had very regular periods since I was 6 months pp. My husband and I have decided to TTC our second, under my neurosurgeon’s recommendations, due to some health concerns and a surgery I need when I’m done having children. We just want one more. Anyway, I’ve been using opks this month and every test has come back negative. I’m wondering if breastfeeding is suppressing my ovulation, even though I’m having regular cycles? Does anybody have any insight here?