Hello mam, PCOS is a hormonal disorder which affects menstruation
and conception at all levels and thus responsible for menstrual irregularities especially delayed periods and infertility
Your thyroid levels are also deranged so doctor gave you eltroxin
keep taking that everyday.
Weight gain is common after meparate intake and in PCOS patients it may take up to fifteen days to get periods after stopping the drug.
In case you still don't get your periods get an ultrasound
done and visit your gynecologist.
Wish you all the best.