If you were truly overmedicated I'm sure you would have other obvious signs than the fast heart rate (which could be due to pregnancy too). Not sure but could your joint issues be because of the effects pregnancy has on your joints
- they'll "loosen up" also in your pelvis to make giving birth easier. Treating HypoT usually is easier
- it's not that common to have a suppressed TSH with such low dose as yours, if I remember correctly your actual thyroid levels haven't been that high either.