Hi Will, welcome and congrats on the new friend!

I think you need two more things:

A dimmer or thermometer to control the UTH: The surface temp of the UTH is important- it shouldn't be higher than 95 (IMHO). Over 100 can cause neurological problems long term. If you think about it, anything that feels warm to you to warmer than body temp (>98.6).

A higher watt- or second bulb/CHE: The heat from the UTH does not warm the air very well. Since you're using a CHE and still not getting the temps you need, you'll need to add to it. Or heat the room more.

You should measure underneath the substrate and above- the first so that it isn't too hot, and the second so that it's hot enough. Check under the hide because it will conduct and trap the heat. You could also experiment with a different substrate.

Oh and that tank seems quite big for a baby- I'd throw in a couple extra hides and maybe fake greenery or something to make him more secure. This is more important if he won't eat.

Don't worry about feeding him for another week. The more you try, the more you stress him out. Get the temps right and then leave him alone for a while. It won't hurt him to miss a couple meals. And make sure that you're feeding him the same as what he was eating before (if you know).
Keep us updated!