I suggest leaving the pH alone. 7.2 is ideal for shocking, 7.0 is fine. Notice that it is back to where it was to begin with.
Shock again to FC 20, recheck after one hour of circulating. Boost FC as needed to try to keep it at 20. It will start holding more and more, eventually you will be able to go several hours between checking. Keep a log book of what you test, what you add, what the prediction is for the addition. Like, test 7:30 AM, FC 4.0, added X oz 6% bleach, goal FC 20. 8:30 AM, FC 15, added Y oz 6% bleach, goal FC 20. It will help you predict when you need to check again.
The formula for how much to add to the pool is via The Pool Calculator
http://www.poolcalculator.com/ First, input your pool volume, then at the bottom, select for Selected Goal Levels; TFP goals, bleach, vinyl if that is what you have.
Then input your test data in the NOW column. For the things you are not changing, put the NOW values in the TARGET column also (CYA, CH, pH, TA). Use your Shock FC as the goal, 20. Select for 6% bleach or whatever chemical you are using.
Moving the cursor over a box will convert that volume into jugs or cups or whatever, be sure to select the correct jug size, big is 182 ox, little is 96 oz.