TSH Level - Rainbow Baby

Cecilia • Mommy to our rainbow princess Manuela Carolina (born Feb 2017) after a miscarriage in November 2015. Baby Boy due March 2020!
I am 8 weeks and my doctor called me to tell me that although my TSH level is normal (2.8) he would like it to be 2.5 during the first trimester. 
My husband and I went on a little road trip and the doctor wants me to start taking medicine immediately and will call the prescription into a Pharmacy near where we are staying although we get back on Monday night. Makes me feel that it's super important! And I'm freaking out a bit. Last year we had our first ultrasound at 8 weekes and I found out I had a missed miscarriage at almost 11 weeks. I'm hoping the medication will help quickly and it's not too late!
Anyone else have to regulate their TSH levels during the first trimester? They said that I would need to get tested again in six weeks to see if my medication would need to be adjusted. Help!