Does breastfeeding make it harder to conceive?

I just stopped breastfeeding my 11 month old last month and also started TTC at the same time. Didn't get pregnant. I've had periods since he was 5 months old. My period symptoms were way more intense this time, I'm sure my hormones are going crazy trying to get back to normal. But I'm wondering if I couldn't get pregnant last month because my milk hadn't dried up yet. Any input is appreciated, thank you!