Thanks for query,
you have irregular cycle due to hormonal
This happens due to anxiety,Tension,Long working hours.Shift duty,or some ovarian disease
like Polycystic disease.
The reason of your weight gain seems to be your steroids
injections.This may alter your hormonal balance too.
So unless we Rule out one by undergoing ultrasound
to confirm your PCOS it is very difficult to arrive at one diagnosis like PCOS or Steroid impact.