TSH level rising for Hypothyroidism?

After having my baby my TSH level was 0.02 and so my doctor reduced me from 125mcg a day to 100. I was tested 6 weeks later and my levels were 1.5. 3 months later my levels are 4.45. My doctor has ruled this as acceptable and a re-test scheduled for 6 months. I'm concerned that my levels will keep rising and that 6 months is too long a wait. Also, I thought any level over 3 was too high.