Hi,
Yes, you are right. During pregnancy Dose of thyroxin is increased to maintain
TSH within reference range. reference ranges as recommended are: first trimester, 0.1–2.5 mIU/L; second trimester, 0.2–3.0 mIU/L; third trimester, 0.3–3.0 mIU/L.
You should contact your physician and get yourself clinically examined and get investigated. They may guide you regarding doses.