This may be hard to fathom, but it does both limit depth and makes it feel deeper.
Your dick is definitely not going any deeper because you're riding high. The pubic bone gets more in the way creating more of a bend on your shaft. It feels deeper because of the crowbar effect your inflicting in her barrel. This stretches the internal surface deeper within even though you're shallower.
I've asked my wife (and my previous partners) how this feels like and I've gotten vague replies. When I ask for details, I ask from an engineer's point of view. When I get an answer, I get a nebulous, "It feels good, but it hurts."
The people here seem to have a better handle on descriptives. We have to because we write about it so much.
EDIT: The last 2 responses were made while I was writing my post. Cjay8inc, get used to people saying "Every woman is different, you should ask your partner." I ask these same questions here for the same reason you do; a clearer explanation.
It's threads and questions like these that make me miss Gillette the most.