Yup I do have the chest clip a little high in the pics, Its usually at his armpits, we werent going anywhere yet! (dh put it way high because I always yell at him for leaving it on his belly!)
I know it looks like he is close to the height line, but really he has about 2.5" before he hits the red line on the seat (I measured today) -
He is also just under 19lbs - so still good without the headrest, although I'll probably put it on soon anyway.
I have him on the lowest slot because the second one is just level with his shoulders without the padding, they are below with the padding on the first slot.
Im going to make some adjustments here soon, but I checked everything and he should be ok with how it is set up now.
I've uninstalled and reinstalled it a few times already and its really easy to use and get nice and tight - so far the only issue I have with it is that I cant adjust the harness with it installed - Its not a big deal though because I usually just leave it tight and only adjust it when he grows and needs to be looser.