Linning of my uterus

Okay ladies. I need help. I was informed back in May that the lining of my uterus was only 3mm thick (normal in order to conceive is 7/8mm) the doctor prescribed me tamoxifen to help thicken it.. I had another vag ultrasound done last week to re evaluate.. well no improvement. My lining is still at 3mm.. they want to put me on estrogen for a month and then re evaluate. Has anyone had this experience? Or can anyone give me any hope? Started taking it. & I feel so so nauseous but it will be so worth it if it helps!