GeorgEGNT,
I had the exact same problem for a couple of lessons. The trick for me was when my instructor told me to look down at the end of the runway. It gives you a much better perspective as to what height you are at. When I was trying to look at my touchdown point it gave me the impression that I was lower than I really was, I would flare too early, lost lots of speed and dump it down from 20 feet. Not so good for the undercarriage
.
Started looking down the end of the runway and huge difference, had a couple of landings where I wasn't even sure we had actually touched down
. Give it a shot.