Well, it sounds like you got what you were after. I approached it with my doctor that I wanted to optimize my thyroid levels and that I felt pretty sluggish on the high end of TSH. He was quite reasonable about it. Although I eventually gave up on synthroid altogether and use Armour now. For that I had to switch docs and use an ND.

So, many labs have changed their TSH scale so that 3 or even 2.75 (I think) is the high end. But yes, you can feel really bad at 6... TSH doesn't necessarily reflect how you feel.

You really do need to give it a good 4 weeks for T4 to make a difference. It builds up in the blood slowly. If you overshoot it, believe me, hyperthyroid is just as NASTY, if not worse, and it'll take a long time to lose the symptoms because T4 has a long half life. So try to be at least a little patient.