Do you have another LFS nearby that tests water with a kit other than API? Taking some water there may be helpful in giving a second opinion, and potentially faster than waiting to order a test kit. I personally know multiple individuals who have tested API and Red Sea ammonia kits side-by-side with API regularly showing higher results than Red Sea.
Other general recommendations:
- I would recommend adding some more rock to the tank, the tanks that I have had the most stability with have all averaged 1-1.5 lbs/gal.
- I use, like, and recommend Dr Tim's One & Only as a great nitrifying bacteria source.
- Until your ammonia reads "0" I would strongly recommend not performing any water changes, if our ammonia levels are elevated like the test shows you need to allow more time for the nitrifying bacteria to establish. If you have to perform one keep it small (1-2 gallons in your system).
- Use RODI water instead of well or dechlorinated tap water.