Still waiting

I was on the depo shot from July till October. Still haven’t gotten my period. But I had to get a biopsy for HPV and I started bleeding and cramping after that but it Wasn’t my period. They just had to cut me inside and stitch me w stitches that melt away on their own.

The test was negative for cancer but I’m still without a period.

What can be wrong? It’s now 4 months since I missed my second dose of Depo shot