I exclusively breastfed for 6 months and then I continued to breastfeed with solids added in until my daughter was 13 months. I didnt get my period until exactly 28 days from the last time I breastfed my daughter. After that it was 31 days then 33, then 46 and then it I finally got pregnant again. I know my dates so well because we were trying from 11 months on. But I remember in between that 33 and 46 day period there was an entire week of hell. I never got a period, not even spotting but I had horrible pains all over, with period cramps, sore boobs, headaches, the works. I thought I was pregnant the entire time and peed on more sticks then I could count but they were all negative. Anyway, I think what you are experiencing is totally normal and the fact that you are still breastfeeding some is going to be a factor in when your body decides to have a period
Good Luck and congrats on the baby