Pregnancy while breastfeeding?

Did anyone get pregnant while exclusively breastfeeding? Some background: I am two months postpartum, haven’t had a period yet, 99% breastfeeding (10-15mls before bed just to fill up his belly before he does his long sleep stretch), and needed fertility treatment to get pregnant with my other two children... I completely understand that you can get pregnant while breastfeeding but my husband got a little carried away. We also made the decision as a couple to not use birth control and mainly use pull out (yes, I know pull out is not always effective) after requiring several cycles of clomid and iui to get pregnant. I would be ok with it but it also makes me a little nervous especially because the plan was not to go back to the fertility clinic for another 3-4 years.