I agree with only offering food weekly and no handling until she's eating consistently. Asking Nick what she was eating before you got her is a good idea too. If she was eating mice then I understand why she might initially refuse rats. Your temps are in range so hopefully it's just a matter of time before her appetite kicks in. I wouldn't worry about her weight. My coastal was a 100g yearling when I got him from Nick back in 2015. He's close to 7ft now.