In your case I would recommend getting an electronic pH meter to rule out that something isn't messing with the titration tests. Get that and a couple packs of calibration standards, and use only DISTILLED water to make the calibration standards. Mason Jars with plastic lids work well for storing these solutions for months.
I will be a pariah here and say to get some strips, the Pool Master kit from HD since it's a different manufacturer and it's cheap, or whatever to get a second pH test other than a Taylor just in case. (Is it possible that one of the chemicals is bad? Yes, unlikely but possible.) The electronic meter is the best bet, but having multiple tests can rule out if there is something wrong with the test you are doing.. Maybe... well, this will get me banned or at least shunned likely... take it to a pool store... as a second test... but ignore their advice....okay?
BUT-- Yeah that's pretty low. Like not comfortable to swim in low... You can raise pH by aeration. It's the same concept as shaking up a soda bottle to make it flat. If you remove CO2, then you are also removing carbonic acid and pH will go up... but at below 6.8, that might not be effective enough. I'd be looking at some baking soda or soda ash. Your water IIRC is fairly soft in Florida so you could get away with it. But if you can tilt the returns upwards or even pump air into the pool somehow, you can immediately start doing this. You can also fashion an aerator out of PVC and use it to suck air when a return is running like many spas without air pumps do.
You can maybe experiment with a bug bucket of pool water and chemicals before you add dozens of pounds into the pool as well to scale up what you actually need. You can calculate what you need in pool math, try it in the bucket and verify that it works before doing it to the entire pool. If it doesn't then I would question the testing....
In most of the rest of the country the water is hard enough (and high enough TA/CH) that letting it ride is better. In general you want to use as few chemicals as possible in managing the pool since most of them you can't take out. In fact in most places the pH will always drift up.
Have you measured your fill water as a baseline? That might give everyone a clue as to what you are up against. If it's low CH/TA then raising it with carbonate ions isn't as big of a problem as it would be for someone like me who can sand paint off the house with the water at certain times of the year.... It would be interesting to see the pH of the fill water as well, as if it's really low.. then an autofill will always bring it down....
