It's always better to report GH and KH in degrees. So your GH is 5dGH and KH is 4dKH; which is is different from your previous testing. Which is good! We won't need to adjust the GH to increase it. I believe the API tests over any test strip (if that's what you used previously). Hang on to the CaSo4 and MgSo4, it lasts forever and you might try fish that like high GH in the future, or if your source water ever changes you will have it ready to use if need be!
As I stated earlier, I think you just need to dose more easy green. I dose my non CO2 tanks to 30ppm K, and I would like to see yours a bit higher. Shoot for 20 to 25ppm K, you will just pump more Easy Green. Unfortunately, all in one ferts lock you in to their ratio, so you will just have to see what happens by increasing the dose as a whole.
If you change 4 gallons and add 4 gallons, dose a bit less than 3ml of Easy Green. That's 18ppmNo3, 1ppmPO4, 12ppmK and .2ppmFe(proxy). Watch the new growth and see if it improves(3 weeks or so). If it looks the same, go to 4ml. That's 24ppmNO3, 1.3ppmPO4, 16.1ppmK and .3ppmFe(proxy). So on, so forth.
Last question. What is your pH? the iron in EG is EDTA and a pH over 6.8 will lock out iron. The Easy Iron seems to be a mix of Ferrous, EDTA and DTPA. But I don't know in what percent each is.