Why do people insist on lowering nitrites in a fish-in cycle? It's a process that is reactionary. You chose to put fish in before the biological filter was in place, which is fine, but you're now accepting DAILY water changes regardless of whether you think you need them or not. The fishes health is dependent on it.
With that said, if you're doing daily PWC's, then you're making the water conditioned to be safe in that process for a full day, so it's irrelevant as to what the nitrite levels are.
The nitrite levels are directly correlating to the amount of ammonia that exists. Why lower nitrites? Leave it alone and stick to the PWC's until you see nitrates and then you expect the ammonia and nitrites to be zero at that point. You are not doing daily water changes to lower nitrites, you're doing them to condition the water that has poison in it to be safe strictly due to the water conditioner.
And plants don't do anything to noticeably lower values unless they are fast growing. Too many people throw around the idea that a heavily planted tank will lower nitrates considerably. That's patently false. They need to be growing at a very fast rate for that to even occur, which is not possible with a typical low-tech setup.
Sounds like you're on the right track though; keep up those daily PWC's!