Certainly a mouse a week is not sufficient. Based on the girth you described, she should be eating large weaned rats or small rats. Do you know if the mice she was eating were live or frozen/thawed? You'll want to start off feeding her the same thing. I'd give her a week to adjust to the enclosure - no handling, no feeding. I think giving 2 mice is fine. Let her finish the first one and try for a second one. Eventually she will need more than 2 mice, so you'll want to try and convert her to rats at some point. Leave her in the tank when you feed her, but never leave her unattended with a live mouse or rat.

As for your setup, you didn't provide any details. I'm assuming you're using an under tank heater. This should be regulated with a thermostat - thermostat probe should be directly attached to the heat mat. You'll set it so the glass on the inside of the tank (hottest part she can touch) does not exceed 90-92°F. You should have hides on both the cool and warm side of the tank. Humidity 50-60% is proper. What substrate are you using? Don't use a heat rock - since she did have one in her other tank, you should inspect her for any burns that may require treatment.

And welcome to the forum and congrats on your new snake