Missed period this month

I’m 6 months postpartum . This would’ve been my third period since having my baby. The last two months I have started on the 24th and 23rd and I usually start to get tired and crampy around the 19th. For July, I had spotting July 6th, and I started to get crampy on the 17th but my period still hasn’t came. Im not trying to get pregnant and it’s been a few weeks since I’ve had but as a precaution I did take two pregnancy tests. One after spotting and one a few days ago. Both were negative. We’re in the process of finding a place to live and leaving our current apartment which has been pretty stressful so I’m not sure if this is related or missing periods when postpartum is also normal?Any advice is appreciated