Hypothyroidism after delivery?

After 5 months of c-section, a routine test found that my TSH level was 250. My doctor suggested me to start 75 mcg of thyroxine tablets. Now, after 6 weeks it was 2.02 and after 2 more weeks it was 1.34. During this period, my menstrual cycles also started. At 8 weeks, I visited my doctor and he said I should continue on the same tablet for one year. Isn't one year too long? Do you think these test reports are not conclusive? I am worried that I might have to continue taking pill for rest of my life...please suggest