There are several ways of lowering soil pH. The problem is, what is the starting pH, and what is pH after an application? Soil testing labs use pH meters, but these cost between 50 and 500 dollars, and they must be calibrated with standard solutions before use. The best way I have found for measuring soil pH is indicator dye. A 2 dollar bottle of indicator dye solutions might do 100 tests. Since cranberries grow best with soil pH between 4.2 and 5.5, the appropriate indicator dye would be bromocresol-green, which turns yellow at pH=3.8, and blue at pH=5.4. How much sulfur to use depends on where you are starting from. If you have tap water from municipal water supply, there should be an annual water quality report available, and this will give the water pH. If there is limestone in your area, your native soil might have a starting pH over 7.

There are many things that determine what a soils pH will be, and all have been clearly laid out here by several contributors. What the soil is composed of, rainfall, and amount of organic matter all play a role in how many free Hydrogen ions are in that soil and soil pH is a measure of that. What is needed to change a soils pH depends on where it is and what is meant to be done. Adding lime (Calcium Carbonate) will reduce the free Hydrogen ions and raise the soils pH while Sulfur adds more of them and lowers the soils pH. A good reliable soil test from a good soil testing lab is a good source of information and they should be able to tell you how much Sulfur needs to be added to make the needed changes. Adding 1 pound per 1,000 square feet when 10 pounds is needed will not do much of anything. Throwing a handful or three of something is more a waste of time, money, and energy than any help. Here is a link that might be useful: understanding soil pH

I grow blueberries both in the ground in raised beds (5 plants in the ground for five years) and in sturdy black plastic plant containers (5 plants in 4 to 7 gallon containers)--that I picked up cheap from a local nursery. Two years ago, I harvested over four gallons of blueberries. Last summer the container plants were a bit of a bust as a late 90 plus heat wave after I'd cut the watering back resulted in the container plants having a very poor crop, but I still harvested nearly four gallons of berries from the plants in the raised beds. They are picked and put into gallon freezer bags and popped into the chest freezer. I don't even wash them, as I use no pesticides on them. I removed my clay soil in 2'x2'x15" deep sections and built the beds up to about six inches above ground level with a mix of 3 parts sphagnum peat moss, 1 part leaf compost my town produces, and 1 part of the clay topsoil. I reused the rest of the clay in another part of my garden. The container mix is simpler: 2 parts sphagnum peat, 1 part leaf compost. The beds have not needed additional soil or peat in five years. I mulch the beds with pine needles (not for the acidity as they don't actually contribute any, but for the fact they contain no weed seeds to speak of). I use bark mulch as a mulch in the containers--it stops squirrels from digging in them and weeds from growing. I use drip irrigation with city water at a pH of about 6.5 or so, and fertilize with Ammonium sulfate every spring, which also keeps the acidity level up. Fafard makes a sphagnum peat moss based acidic soil mix, so that's an option if you can get past the sphagnum peat moss issue. If you're only growing enough blueberries for you and your family, you are not really going to need a lot of the stuff. It's worth noting that for every person who thinks sphagnum peat moss is not a renewable resource, there's likely another who thinks the opposite is true. Here's what I know: In the US, our ubiquitous Canadian sphagnum peat moss comes from a country that has a lot of it and only harvests a small amount of it, and reseeds the harvested areas with ... sphagnum peat moss, which in the university greenhouse collection I help maintain grows quite quickly--I frequently have to cut it back to keep it from overwhelming our carnivorous plants that grow with it. In North American bogs, the moss grows several or more inches a year. The harvested bogs won't be replenished soon, but they aren't exactly turned into parking lots either. Then too, the harvesting process is not very carbon intensive in the scheme of things. You can read more about this perspective on the topic here: http://www.theecologist.org/blogs_and_comments/commentators/other_comments/1780209/the_truth_about_peat_moss.html and here: https://garden.org/urbangardening/?page=august_peat

See if you can find Soil & Water dudes to talk to instead of Cooperative Extension. How old is the construction? If it is more than 5 years old, then alkaline leaching has already occurred, and you've got what you've got. My personal experience, living in a lime pocket among an assortment of lime pockets, is that most gardeners have been quite thoroughly brainwashed into thinking anything in the east has to be acidic. It just isn't so. So when confronted with an alternate reality, they come up with excuses. Concrete leaching is a classic. Older concrete doesn't leach, and the leaching doesn't travel much. I don't know how many times I've been told that I should stop liming, and then I will have 'normal' acidic soil. If you want to know how the neighbor grows camellias, go over and ask. And no, my soil doesn't fizz either, and my pH, and calcium numbers are very similar to yours.