There's something important to distinguish here: there's dosing ammonia to test a fish-less cycle, and there's dosing ammonia to raise nitrate
Don't dose ammonia higher than 0.50 ppm to "test" the bio filter - that could be dangerous to your fish, and is unnecessary. Your cycle didn't stall or break down, that's not possible.
On the other hand, some people use ammonia to raise nitrate, but they are adding enough to raise the ammonia no more than 0.25 ppm at most at a time.
For now, I would stop testing ammonia at all; you're cycled. Purchase a nitrate and phosphate test kit from Salifert and confirm both test readings. If they are truly low, I would feed the fish more, or at that time consider dosing phosphate and with nitrate or ammonia. But I wouldn't get into this just yet, see where the tank goes