Am i converting to t3 adequately as tsh:15, t4:20 while t3 quite low at 3.9? 1st time t3 tested.(100mcg levo, prev on 125 daily with t4:25 tsh:0.7)

Hypothyroid and T3: If I understand your question, it appears that your TSH is mildly elevated (not sure of your normal range, though). You probably just need a higher dose of levothyroxine. Or maybe you are intermittently taking it with food, which can impair absorption. T4 to T3 conversion is almost never a problem, and you don't need to take supplemental T3.