I have two Britax seats for my girls and I’m pretty sure that’s the way they are supposed to fit. The lower straps are supposed to go across the tops of the thighs, not the waist. The crotch strap sits much lower than the belly, to keep the straps down on the thighs. This is the way a 5 point harness is supposed to fit, so that in an accident the shoulders and thighs absorb the greatest impact, not the belly where the internal organs are. You don’t notice it as well, but in the little infant rear facing seats the straps also go across the thighs, or they should.
The carseat clinic sounds like a good idea, too. I went to one and learned a lot. They are so very helpful.