Do you have recent labs and reference ranges?
Cytomel is much more powerful than
Synthroid (about four times more powerful). So, if you subtract 25 mcg of Cytomel from your regimen, you ought to be adding more like 100 mcg of Synthroid. It sounds like your doctor might have left you undermedicated in the switch to Synthroid.
I have no personal experience with Cytomel-only therapy, but I do know of people who have been treated with T3-only temporarily.