Gall,welcome to the world of frustration in flight training.
Number 1; very important to understand and accept....everybody struggles with this one, there are no "natural pilots". Some people take less time but everybody struggles.
The cure is a little more elusive and difficult to describe.
Your FI is right, keep flying the aircraft, not only into the landing but till you are stationary on the taxiway.
What he (we) means by this is that you keep manipulating the flight controls till you are stationary. Rudder, elevator and ailerons.
Mentally don't think of landing as a
different phase of flight, block it out and keep flying the airplane with idle power. eventually you will touch down in a nose high attitude since you tried to keep flying you kept increasing the angle of attack by increasing pitch till touchdown.
Mind you, don't keep pulling back till the aircraft stalls 10 feet above the runway, no keep flying it just above the runway and mentally tried to avoid touching down. Its a trick but it works.
The generation of lift is not linear (because of the drag curve) but think of it as this:
The average light airplane requires 60 knots of airflow to fly therefore at 30 knots you have half the lift and at 15 knots a quarter.
So at 30 knots you only have half the weight on the wheels or the airplane is still flying "half" .
Do you see know why you have to keep flying (manipulating the flight controls) all the way to stationary?
Even at taxi speeds you use the elevator to alleviate the weight of the engine on the nose wheel. The rudder and the elevator are also in the accelerated flow from the propeller so active to a very low speed.
With some aircraft you can "pop a wheelie" from a standing start because of the accelerating slipstream.
But that is a different lesson.................
"just fly the plane" is a pitiful answer
That's a bit harsh about a FI that neither of us knows.
Sometimes students just need to listen without questioning
everything we say.
You don't always want to floor a student with 3 hours of theory with every question. Especially in the airplane.
Sometimes a "trust me just keep flying" should suffice.