only trustworthy testkits out there are pH, KH, and GH.
As long as you are dosing consistently, there really is no need for PO4, NO3, Fe, or other testkits. So save your money.
How much of each of Macros/Micros are you dosing, and of what product?
Do you have CO2?
1ppm is OK with PO4, as long as you don't let it bottom-out. Your algae levels will let you know if it does. So if no GSA, you are probably fine.
450g Planted Discus Tank - Work in Process!