Neither her lowest nor highest heart rate appears to be unusual. When we sleep, our heart rates often drop into bradycardia. We're asleep for many hours, and not doing anything that requires a faster rate. If she doesn't get a rate of 46 beats per minute *during the day,* I don't see anything worrisome.
As for the tachy, 152 is high, but if she is emotionally stressed, that is not a rate to worry about. As I'm sure you know, people with autism *are* stressed a lot!
The other symptoms you mention--chest pain, dizziness, sweating, weakness, and even trouble talking--are consistent with panic attacks. Please google panic attacks to see if you agree.
When you see the doctor, ask him/her if your daughter has any real signs of heart trouble. At her age, it is *extremely* unlikely, but he may order some other tests to be sure.
If her heart gets an 'all-clear' after that, then you may have to take her to a specialist in emotional problems to see if she can be helped via that route.