I had this problem with my pool too...It's difficult to know your exact pool volume, especially with pools the size of yours, mine, and PoolStored. I know that 36,000 is a slight over estimate for me, but that's what I use for estimating. I'd rather have a little chemical left over then not have enough. When it comes to actually dosing, I add slowly until I reach my target level. Your 34,000 gallons probably has about 800 square feet of surface area. If that's the case, then each inch of water level is about 500 gallons as well.
90% of the time you do not have to be perfect..if you're shooting for 6ppm chlorine and you hit 8 on accident, who cares? It'll come back down and you can try adding a little less next time. The time when it is important to be as close to perfect as you can is with the OCLT. If you're a little high, it's okay, but it's important to test and know exactly where you are so you can accurately measure your losses.
For everything but the OCLT, you can also use a 5ml sample and have every drop equal 1ppm. You'll use half as much reagent. Good for a quick check when you don't have to be perfect perfect.