Breastfeeding and pregnant?

Is it more difficult to get pregnant while breastfeeding or is it still about the same probability? I have heard it can be more difficult cuz if you are breastfeeding you may not ovulate..... I am still breastfeeding my 12 month old but only at night before I put her down for bed (we have been in the weaning process for a while). My SO and I decided we are gonna try for baby #2 soon so I just got off BC because I have PCOS (along with other health issues) and it took so long to get pregnant with our first. But recently I have been having some symptoms that are different from just AF..... I am just having a hard time believing I could be pregnant with all the issues we had trying before and the fact I am still breastfeeding.