Welcome, it sounds like your practice is paying off. You just need to add a new technique or two.

First, the LAST thing you do to slow down an airplane is to point the nose down! That has no other result than to make the plane go faster.

Try this: line up on the runway and hold the airplane wings level and body level, to VERY slighly nose down. Then pull the throttle back to idle. The natural tendency of the plane will be to nose down on its own to hold the same airspeed. You are going to slow it down by simply holding it level. NOT nose up. If you do give it too much elevator and it starts to nose up, then stop. Just hold that amount of elevator until the nose drops to level on its own. We're trying to stop you from starting a PIO Pilot induced Oscillation where you just start chasing the nose up and down.

Now if while holding the plane level it apears that the plane is stalling and falls out of the sky, then you need to hold it slightly nose down and hold a little of that airspeed. OR add ONE or TWO clicks of power on the throttle stick.

As you get better at this you will reach the point where the plane runs out of airspeed, you run out of up elevator and the plane touches down gently as slowly as it can all at the same time.

Good luck