Welcome to the forum Basil!
My summer pool last year was exact same size as yours, it's a wide shallow pool so the CL loss is high at about 4-5 ppm per day when the weather is 30C
Using the cheap 1.5% tesco value bleach we get here in the UK that's about 1.2 - 1.5 liters every day for this pool which is a lot more than you have been using although your bleach may be stronger so you would need less. As others have said poolmath is your friend....!
Taylor kits are difficult to find outside the US, for a small Intex pool I get by with a DPD tablet kit and even an OTO kit will be fine, all of my test kits came from ebay. But you do need to test daily and make sure your CL does not drop too low
I got fed up with cleaning cartridges daily so I got an Emaux 14" filter with 0.3HP pump, goes for several weeks without any attention at all. Biggest hassle for you will be setting up & connecting the filter to the pool but once it's done it looks after itself.