Hi I Am 26yrs Old. I Had A Normal Menstrual

Hi I am 26yrs old. I had a normal menstrual cycle from the beginning and i have hypothyroid. I am on medication from 8yrs, my thyroid is normal but i daily take thyronorm of 50mcg as prescribed by my Dr.
I was having irregular menstrual cycles my Doctor scanned and prescribed me Myonext and Diane for 6cycles and then to stop. I did the same but only for 2months it was proper again my menstrual cycle is irregular so my doctor prescribed me Meprate, Tamik BC, Diane and ChromiNAC A. My Doctor has advised me to take Myonext life long. Is it realy necessary.