Hey, I enjoyed a lot your idea, changing size to solve the puzzle is awesome, more even that you need to "get hit" to decrease your size to achieve the puzzle solution
But it actually didn't quite work at the third level, there is a coin to get you big, you push the button, get hit by the worm, decrease your size, but in order to go towards the door, you would need to get big again, but the Heart in the second part don't get you big, so there was no way to get past that level