You might get an independent mechanic (one who is familiar with 172s but not the guy looking after this particular 172) to have a look at it. I am a hair under 5'7" and have no trouble reaching stuff in the 172, but the 182 and 150 are better fits. The 172 was built for long people.
-The seat stops might be in the wrong places, stopping the seat from rolling as far forward as it's supposed to.
-The rudder system might be out of rig; see that all the time in older 172s. The pedal faces are supposed to be something like 6-1/2" from the firewall. Cables stretch, pulleys wear. And a good mechanic will watch the service manual for adjusting all that; the nosegear is the primary rigging datum for the rudder.
-The elevator system might be out of rig; see that too often, too. The elevator stops must be set for proper travel first, then the cables adjusted to get proper yoke travel. An out-of-rig system can make it difficult to get adequate authority for flaring.
In short, make sure the airplane isn't at fault before you go spending a heap of money on fancy cushions and pedal blocks. Maybe go sit in a 172 at another school altogether for comparison purposes.
Dan