S.K.
We had to do the same with my daughters tonsils. Like you, I knew she would snort and snore and toss and turn. She would cry out in her sleep but not really be awake. She was never comfortable. She also avoided sleep like the plauge. She ended up developing ADHD because of the sleep apnea. Her ped never said anything and she also had the upper reseritory infections constantly. She never had tonsilitis either. But we had to have them removed because of an article that we found explaining what was happening to her. I was horrified and took her straight to the ENT. He took one look and asked me when I wanted to do it. He said on a scale of 1 to 10, hers were a 12. But I have no idea if there is some official scale your doctor was going by.
The symptoms you describe will absolutely wreak havoc in your daughters life. When we got her tonsils out her life changed so much. The snoring went away and never came back. She stopped getting sick too. But it was too late to undo the behaviors she had developed because of the sleep apnea. The article that we read said that if it's not dealt with before 4-6 years of age, ADHD was a given as a result. You are getting this done at the right time. Ask them about the tonsils too. We did tubes for ear infections at age 2 and adnoids then. I wish we had done the tonsils at the same time.