Your soil has dolomite limestone added to it, so the pH will be buffered to particular level, somewhere around 7.0 is what most commercial mixes are buffered. Your soil testing at 7.1 would lend this some credibility. Usually you can deal with this high buffer by feeding at about 6.3 or so. Your soil pH will drop down to around your feed level, then slowly rise back up as your soil drys. A lot of growers mix aluminum sulfate into the soil when first preparing. This brings the initial soil pH buffer down to a more ideal level. I grow in Promix and add 4 grams aluminum sulfate per gallon of soil. This brings the pH from around 7.0 down to 6.5 - 6.6. I feed at 6.3 and my ph soil drifts from 6.2- 6.3 up to 6.5 - 6.6.
If your feeding at 4.2, you need to get some pH up and/or pH down to get your feeds, and plain water waterings, to around 6.3. What brand soil pH meter did you buy? In my book, Accurate 8 is the only accurate one. You will need to get a liquid pH pen to test and adjust your feeds if you don't already have one.
It appears that you have everything under control for now. Start managing your pH better and you will have a great grow.
Also, I think your soil is pretty hot. I would back off the nutes some, i'm not familiar with what nutes you are using, but usually never go over 1/2 the concentration recommended on the bottle. Water when the pot feels light, your 3-4 days is not uncommon. Water until you get 10-15% of the amount you pour in to come out the bottom. This keeps salts washed out of the soil profile.
