2 things can cause heavy eggs.

over mixing. it makes them kinda tough. adding another liquid like milk before the eggs are mixed. oh..kinda a third...but if the veggies are really moist, it adds "water" which flattens the omlette too.

tip:

separate the yolks from the whites. beat the whites until they form soft peaks. mix up the yolks and fold into the whites.

can you tell i cook all the time.

now you made me hungry!