Wondering about birth control and sex

So I just had a baby 3 months ago and I'm on the low hormone both control or whatever because I'm breastfeeding. I've never used this one and I'm wondering if I can get pregnant well on it or does it work the same as regular birth control? I had a dream the other night that I was pregnant again and I told my husband so he's freaking out a little. I've been having strange periods since I had my son so I can't exactly time it.