My friend, you’re very lucky you haven’t fried your pump. Or otherwise damaged your fuel delivery system. Driving around with your empty light on is asking for trouble. The gas cools your pump as well as running your engine.
My guess is that at the first station you had run to gas down to the level where you actually got air in the line and it took some tome to get pushed through the system. And you continue to do that intermittantly. You, my friend, are courting a breakdown.
Do you realize that it’s just as inexpensive to fill it everytime it gets to 1/4 as it is to wait until the light comes on?