PPM's vs. Feeding by measurements

So Im a little confused as to exactly how I should be feeding and how much. Im using Dyna-Gro Foliage Pro and Protekt. I bought their Bloom, but will most likely continue FP throughout flowering with maybe one mixed dose of Bloom/FP for a P boost if needed. I have only been doing small feedings throughout the grow based on various peoples posts and their own feeding guide using between 3-4ml FP and 4-5ml Protekt per feeding on a feed>water>water>feed schedule. I flipped to 12/12 yesterday and transplanted them all into their final 5 gallon smart pots about 5 days ago amd all are looking beautiful.
Now that Im going into flower, I just want to make sure Im doing this right. I recently purchased a TDS meter to measure my feeding ppm's and noticed that its quite a bit lower than most recommend. I alternate between tap/RO water. Our RO tank is lretty small, so trying to water 8 plants in 5 gallon pots from a 2 gallon RO tank wouldnpotentially take hours.
The tap comes out @ between 95-110ppm (well water). The RO comes out at 5ppm. Now, with my feeding today of 4ml Foliage Pro, and 3/4 tsp. (~4ml?) of ProTekt per gallon, my final ppm was 350ppm using RO. I only fed one plant that is looking particularly hungry (both of my 2 White Widows are showin some yellowing on their 2 lowest leaves). This would mean with my tap water my feeding ppm at this dose would be around 450ppm. I always adjust ph to between 6.5-6.6.
Im growing in FFOF mixed w/ ~20-30% pearlite. From what Ive been reading, and by Dyna-Gro's own feeding chart (I tend to research other peoples feeding schedules and kind of find the most consistant info and use that), most whonare using soil with Dyna-Gro are feeding between 600-800ppm. Granted, some of them add other nutrients as well, but this just seems drastically low, right?
In order to reach those kinds of ppm's I would need to double the recommended dosage or more and that just seems like a terrible idea and a good way to burn them.
My question is: should I be going by the measurements and stick to what Im doing, or add more to raise ppm's to recommended levels?
Heres a pocture of the 2 plants that are yellowing on their lower leaves. Nothing major, but thought Id try a feeding on only these two to see if that would correct it.
The White Widow with the yellowing (are widows known to be N hungry?):


Heres the rest of my room, all others look just perfect:

Don't worry about one leaf at the bottom pull it off ..about the feeding the EC meter always not set doses so for young small plants first like 0.4 EC value then slowly when they grow building up towards 1.2 that means when they are like 12 cm in the beginning up to when they are like 30 cm...if you get yellowing like that it means they want more ...I had the same with my strain what I am growing now..with nutes and additives I was running 2.4 EC in late veg to early flowering ,,anything less and they had that top new growth center yellowing.... now at the end last 3 weeks I am down at 1.8 EC .I use reservoir with my Coco grow..if the EC goes down I use a bit more nutes and if it goes a bit up ,then I only add some water to get it a bit lower ...if it stays ,,then I know that I am spot on correct.. .try upping your nutes a bit..its always depends on the strain...the bottom pics probably can handel 1.8 EC (or more)

Why my EC was that high in late veg was that there was also Humic and Kelp additives which pumped up the reading..they don't really mean nothing ,,they wount fry plants even the additives where giving high EC reading...I was looking at my plants and they wanted more...meaning the new growth in the center was a bit yellowing like that,,,when I upped the nutes it went away..

Younglings get 100-250ppm, Veg between 400-800ppm, and flower 800-1400ppm. In ocean forest soil.