Need assistance in understanding Alkalinity adjustment for CYA of 90-99 range

This is the 3rd summer that I've had my pool, and I am still trying to get it right. I relied on pool stores for test results and suggestions thus far, and water hasn't ever been quite balanced. I decided this year when I opened my pool, I was going to take a different approach and use the BBB method.

I am hoping someone can help me understand my current test results and confirm plan to address issues. First of all, I used the Taylor K-1004 test kit, double checked with the Aquachek test strips, AND has my local pool store test the water as well. Here are my findings:

Test Pool Stores Results Taylor K-1004 Results Aquachek Test Strips
Free Chlorine 7.92 5 3-5?
Total Chlorine 8.01 4 10+
Combined Chlorine 0.09 0-1 NA
pH 7.8 7.6-7.7 7.8+/-
Hardness 250 NA 250
Alkalinity 57 w/stabilizer correction 100 40-80
Cyanuric Acid 99 NA 51-99 (darker than 30-50 range but lighter
than 100+)
Copper 0.1 NA NA
Iron 0.1 NA NA
Phosphate 0
TDS 500

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My CYA was too high last year(154 I think?) and I decided to wait to see what happened over the winter and recheck in the spring. My first check of CYA this year was done on 6/16/2017, and it was 90. Better than last year, but still nowhere near ideal. I'm using the BBB method, drained 1/3 of my pool on 6/17/17, so I'm not sure how the heck it rose to 99 in 3 days? I'm assuming it was pool store error as the Aquachek test strips show my CYA level has dropped since partial drain/refill. Should a drain of 30% have resulted in lower CYA levels?

Based on today's test results and input from a pool math calculator app, so far I have added 112 oz of baking soda to increase the Alkalinity; 49 oz of muriatic acid; and will add 166 oz of 10% bleach tonight. I will recheck alkalinity in 6-8 hours and add more if necessary (app says to add 2nd dose of 140 oz). Does this seem like a correct plan of action? In what order should one add chemicals (pH, alkalinity, chlorine when pH and/or ALK is in range? ) and how long do I wait before I add the next one? (ex., baking soda to raise Alk then wait 15 min to add muriatic to lower pH?)

I have ordered a cyanuric test kit and hope to have it yet this week so until then, I am at the mercy of the pool store's results and the Aquacheck test strips. Until I can test the CYA myself, do I need to adjust the alkalinity due to higher CYA levels of 90-99, by assuming TA-1/3CYA=Actual TA?

Thanks for taking the time to read this.
Wendy

In-ground concrete 16X36 (26,000 gallons approximately) 55" from bottom to top of coping in shallow end; and 9 ft (?)in deep end; Hayward DE filter (with brand new grids) with Cellulose Fiber for the media;Taylor Test Kit K-1004; Chemicals: 10% bleach for sanitizing; liquid muriatic acid; baking soda; and borax,