So I am waiting for my hair to fall out

From what I have been told and what I read my hair is supposed to be gone by now, or at least thinning. The consensus seems to be 2-3 weeks from first treatment, or 15-16 days, with most people waking up in the am with hair all over their pillow and in the bed. So each night I go to sleep running my fingers through my short hair wondering what the morning will bring, but shocked when I get up and its still there. Maybe even needing another haircut soon as I had it done last five weeks ago. I have the wig ready, and when I go for treatment the nurses are amazed I still have hair on my head. Does it mean the dosage isn't high enough and isn't killing enough cells, healthy and cancer cells? Does it mean cutting my hair off early gave it a little more strength and made it more resilient? Probably will never know the answers to these deep questions, but I am grateful every day I have hair.