Thyroid Meds and cycles

I was diagnosed with mild hypothyroidism after my miscarriage in Feb. I didn’t start Synthroid until June. First month was great, my hair stopped falling out. Now this month it started back and my cycle is 6 days late with a BFN after 2 rounds of Fermera. Dr is suppose to be checking my levels. I just feel completely lost! Has anybody else had a similar issue?