Cycle issues

I’m 36 years old and ever since coming off birth control a few years ago I have had an issue with getting a regular period. I had to use letrozole and a trigger shot to get pregnant and it took me months to get a period again after having the baby. Finally got it back and then it disappeared and I hadn’t had a cycle in 90 days. My gynecologist prescribed me progesterone and I took it for 10 days to generate a period. Now it’s been 45 days since I last bled and nothing. I am so concerned and don’t know what to do or why I’m not getting a period. We aren’t looking to have another baby at the current moment but not having a cycle is honestly really concerning and my doctor seems to brush it off and said if I go 90 days without a cycle again I will have to take another round of progesterone.