This reminds me of the "10,000 hour rule".
Feedback and reflection are the way to get better.
Reading between your lines (with due respect), it feels like you need a language for the elements. It's overwhelming to think about it in terms of "there's just a look about them that I can't put my finger on".
You have to break it down into elements: the lift, the thickness, the rim, the foot, the finish.
At the risk of sounding like a broken record, this is why I found Raffan's book so useful. He gives you that language (not that I am remotely fluent yet ). He also shows different sketches, Goldiocks style, with "not enough", "too much", "just right" variations. He also gives a bunch of templates that you can trace and print and use for your own forms. Perhaps most useful to me was his discussions on how curves take off and resolve. This is gradually getting me away from thinking "I'm going to make a calabash" to a more organic: "This amount of return on the lip feels good, given how I've chosen to take off from the base."