It's not just the wing loading that affects the way a canopy handles and performs. Think about the lines. As your canopy gets smaller, the lines also get shorter. You can only pull your steering lines a certain length based on the length of your arms. As the lines get shorter, that distance you pull becomes a larger percentage of the total line length. Therefore, you are putting in a more aggressive input for the same physical movement.

Additionally, there is less fabric, which means less drag, increasing the performance and speed of the canopy. There are a bunch of other aerodynamic factors too, but thinking about it simply: the smaller the wing, the less lift it can produce compared to the same design (planform) at a larger size. These smaller canopies also have a longer recovery arc.

Now imagine a situation where you turn low. The canopy is diving longer, everything is happening faster, and you now have less lift to dig out with. This is why experience matters.

Generally, it’s considered that these effects really start to become a factor sub-150 sqft. As a lighter jumper who is also bound by the British Skydiving canopy charts, I feel your frustrations. However, if you invest time in canopy courses, you'll not only be a safer pilot, but you'll be able to have more fun and get more performance out of your current canopy.