Thyroid problems in pregnancy ?

hi guys ! I need to know if someone's inbthe same boat as me. I am almost 12 weeks and I got my blood work back and the midwife called me to tell me that my thyroid was low (I'm pretty sure she said it was low and not high) nd said I needed to get on medication for it. I go to get my prescription next week. But I am now so worried about miscarriage and I can't stop thinking about it. I saw the heart beat on the ultrasound at 8 weeks but I have yet to hear it at any appointment because my heart bear was too loud. has anyone had this issue also ? shed some light please..