I wasn't sure where to put this so, please move if it would fit somewhere else better.

I'm 5 months PP and I've had 3 cycles. I had my first around 2 months PP but wasn't sure it was my period until 28-30 (wasn't tracking too closely) days later I had another period and 28 days later I had my next period. I'm now on CD 41 with no period in sight. I've taken a test every few days just to make sure and they have all been negative. I am breastfeeding but I figured since I have had three regular periods, it didn't mean much, but now I'm not sure.I'm just wondering if this is normal PP cycle stuff or if I should call my doctor?