Tom Barr is certainly well respected in this hobby and the Estimative Index is certainly a good system to start with but I will ask you one question; how are things going? If the fish are healthy, the plants are growing well, and you don't have any major problems with algae then you are probably doing just fine. Unless you have calibrated your nitrate test kit against a known NO3 concentration your test results are probably off.
The first year or two I used various methods of dosing and followed them to the letter. The last "formal" dosing system I used was the Estimative Index. It is a good system and gave me a good basis to start.
Eventually I started looking at my tank, fish, and plants more closely. My tanks are planted maybe a little heavier than average, I have about 2 WPG of light and CO2 on my tanks, and my dosing level is about 2X the "recommended" EI amounts along small supplemental doses of Flourish (Comprehensive) and Iron. I found there was not "magic number" for my aquariums (my NO3 regularly is in excess of 30.0ppm). I do a regular weekly 35% water change. My plants grow well, my fish are healthy (my Corys spawn regularly), and I have minimal problems with algae.