Very long down regulation itself should not affect your egg quality. However your IVF protocol does not sound routine. The relatively high dose of Menopur used suggests low ovarian egg reserve. Endometriosis and low egg reserve are however major factors in low embryo quality and success. Also the sperm quality has important part in embryo quality. Difficult down regulation can be controlled by short, antagonist protocol. I would suggest that you see a fertility specialist to review your records to give a realistic, tailored success rate of another IVF cycle.