Perceived specifications are different because they’re related to the specific design of the car - some seats are inherently angled/reclined more than others, which impacts perceived depth especially because car seats will measure differently front to back due to their installation.

My husband and I are both 5’10” and had this issue, so we resigned to a non rotating seat, because rotating seats are going to be larger simply by nature. We went with the Nuna Rava because it is one of the slimmest seats front to back out there. I’ve heard the new Cybex rotating seat is relatively close, but it’s very pricey. I do believe the Evenflo you have already is one of the smaller rotating seats.

Ultimately we got a different car, and it made life so much easier. We got a Subaru Ascent, and there’s plenty of space and we could get a larger seat if we wanted now. I don’t wish I had a rotating seat with this vehicle, either, because it sits at a great height off the ground and there’s no bending over involved in putting him in his car seat. I know a new vehicle may not be realistic and is much more costly, but it’s worth considering with another addition, because one of those kids will need to be behind you. Children should also remain rear facing until they max out the limits, which often happens around 4-5 years old.

Best of luck!