Hello Dr. I Am 45 Years And From Few Year

Hello Dr.

I am 45 years and from few year ago I have suffer from anxiety and depression in the menstrual period. I went to the psychiatry and she prescribe mirtazapine, the first time I use for around 3 o 4 month. And Now the problem has coming again, but it's just happen in my period menstrual, the problem is that I am suffering of insomnia and I can't understand why that happen in that especial moment. right now I'am under mirtazapine treatment and in this menstrual period suddenly I started again with insomnia and I workout almost every day, 1 day a weel I take yoga class for beginner , Normally I used to do breathing exercises, and I don't know why this problem never end, Used coming especially those days.
Please I am desperate, what can I do.