My 4 week old is an infant carrier, and of course we all know a rear facing seat straps are supposed to be at or below baby’s shoulders. My question is, how far below is too low? She gained some length seemingly overnight and she was extra fussy in the seat today when we drove a half hour each way to go get groceries. I noticed the straps start so low in the back now — like half an inch lower than her armpits — and when we got home I changed her into pajamas and there was a full indentation of the car seat harness on her poor little body. Shoulder straps left her neck red on the sides, indent from the chest clip, straps going down her body, crotch buckle and straps, all of it. I don’t feel that it was too tight, I always tighten it until I can’t pinch the strap anymore and she’s never had an issue before. I thought okay, easy fix, we will just move the strap up to the next slot. Well…maybe not such an easy fix? The next slot is about a quarter inch ABOVE her shoulders. I’m not really sure what to do at this point.