I don't know that much about ammonia dosing. If I were you, I'd stop dosing and watch the levels drop on their own. Bacteria builds up quickly, I'm sure by now you have enough beneficial bacteria to support a small, hardy fish once your ammonia and nitrite levels drop to 0 and you do your first partial. My neighbor who helped me with my tank told me, after watching me mess with it incessantly, that I needed to step away and leave it alone. I'm a little OCD!