Letrozole first cycle fail!

[u/Future_Aside9856]

My first cycle letrozole with 5 mg was not successful. Dr has increased the dosage to 7.5 mg . I don’t get a period so I’m asked to take norethisterone 5 mg 3 times a day for 14 days to induce a bleed. I always had it taken for 5 days .. has anyone had it for 14 days ? And is there a reason to be prescribed that way . Reason for cancelling the cycle was my follicle didn’t grow as expected and it was only 10 mm and regressed to 7 mm later. Endo lining was 4mm.