Breastmilk help!

Hi! I gave birth 9/24/21, and got the depo shot two weeks after my six week checkup. I only got the one shot and no other BC. I am not breastfeeding my daughter nor pumping. I lost my supply when she was about 3-4 months old. I am not on my second period, and now im producing again! I was 5 days late on this period and could have been pregnant. I took 2 tests before period showed up and they read negative. I had a miscarriage 3 months before conceiving my daughter december of 2020. Whats going on??