2 Months Postpartum & Pregnancy!?

I recently just gave birth to my beautiful little girl in July 2018. I had a great labor and delivery with NO complications or pain or anything. Everything was perfectly fine, as if I never had a baby. I breastfeed my baby only. She’s not on a scheduled time, it’s just on demand. After I gave birth, I had the usual bleeding for like 2 weeks, almost 3 weeks. My boyfriend and I started having sex within those 2 weeks up until the 6th week. At exactly 6 weeks I got my period (September 3rd, 2018). I was a little heavy for the first 2-3 days and the rest of the days were normal. My normal period before my pregnancy was 7 days. From what I can remember when I had got my first period (6 weeks postpartum, 09/03/2018) I was on for about 5 days (09/07/2018). After I was off my period, my boyfriend and I begun having sex every other day again. It is now October and I am nervous if I will get my period or not. If I am pregnant again, my boyfriend and I will keep the baby, we were planning on trying for another baby when our daughter turned 6 months anyway. But, I am just wondering if there’s a possibility if I can be pregnant again even though I am breastfeeding (on demand). Also, I had a postpartum check up but my dr canceled my appointment due to her having an “emergency” and then when I tried to be seen I was “over the 6 week check up”.