Plants look good. Sounds like the last meter you MUST have is a PPM/EC meter, which will tell you exactly what your giving your plants as far as nutes go. Using the suggested amounts on the bottle is probably close, but probably really isn't good enough, you want it perfect for optimum growth. For example, as your plants develop, their nutritional needs grow, so what you are feeding them at 4 weeks, is not the same as what they need at 8 weeks, at that point you could almost double that amount, but guessing, which is what you are doing following recommended amounts, isn't the way to go. Real pot growing is a science, and if you want optimum results, which I'm sure you do, after all it is an investment in time and money to produce a healthy plant, Look at this way, A good combo meter that tests everything, PH/PPM will set you back $150, but if you get say, 1.5 oz per plant at a street value of let's say $250 per zip, you will have paid for it on your first grow. If you want to do this long term, you 1st need the tools to do it right, so get a PPM meter, and your plants will love you. Finally, ALWAYS add PH adjuster after you put your nutes in the water, because the nutes WILL affect your PH.