In the current scenario, you should get your serum beta-hCG
levels assessed as urine pregnancy
tests have already been done too many times with no effect. After a delivery, hormone imbalances can crop up due to various reasons like getting back on track after prolonged exposure of the body to high progesterone
levels during pregnancy, weight disturbance during and after delivery, feeding and the grueling task of taking care of a new born creates stress
and this in itself disturbs cycles and as you said, infections. You need an evaluation by a gynecologist to conclude. Hope your query has been answered. Take care.