I wouldn't stop out right, just taper down every 5 days or so by 50mcg.
It would probably be useful to get a blood test for reverse T3 as well. T4 only therapy isn't typically a good idea. If you have too much T4 in your body and it can't convert to t3, or the t3 is pooling up in your blood because you have low cortisol, then T4 will turn into reverse T3. Reverse T3 is a mirror image of T3 except it is an inactive hormone. The problem with this is, it binds to T3 cell receptors and actually prevents real T3 from getting in.
This will cause more T3 to build up in the blood and your body will turn more T4 into RT3 in an attempt to avoid excess T3 in the blood.
It's a vicious cycle. If you have high RT3 that is probably why you aren't feeling any benefit from the thyroid meds you're taking.