i love pan fried chicken usually with some tumeric, salt, pepper, rosemarry, and evoo. Anyways, I don't like to get my thermo dirty everytime, and sometimes i get it a bit overdone, sometimes the oppsite
There isn't one.
The only reliable way to determine doneness of a chicken breast is to use a thermometer. If you didn't have a thermometer then you would have to cut open the breast to confirm. Outside of those the only other method is experience. e.g. knowing that it takes 5 minutes per side to cook a breast of X size, in Y pan, on Z stove, at M heat.
Given that you own a thermometer, it's kind of silly to ask for another way. Use it.
I do it restaurant style. I sear it nice and golden on one side, flip, sear a minute or two on the other, and then bung into a 350 degree oven. 12-14 minutes and it's done. (Obviously you can only do this if you have oven-safe frying pans). No need for thermometers, maybe a quick poke to double check.
You can work on learning the finger test, but during your first experiments, I would cross-check this with your thermometer to make sure you know what it feels like.
Personally I prefer to only trust a thermometer, as then I can be absolutely sure (within the margin of error for the device) that my food contains no living harmful bacteria to hurt anyone I am serving.