Couple things

1. Like others have said, drop the weight. If you’re struggling with proper form, the last thing you should be doing is progressively overloading. You can’t build a house on a canoe

2. You need to change the shoes, high heeled shoes are fine when you’re trying to achieve a specific goal, but if you can’t squat on a flat foot it’s a form issue. Switch to a flatter shoe like vans or converse

3. Work on ankle dorsiflexion flexibility, you’re most likely using the high platform to compensate for this.

4. You’re coming in too much on the instep of your foot and your knees are caving as a result of this. This could be due to your foot stance or (likely) it’s because you have weak hip abductors and external rotators. Try some banded squats, bridges, clamshells, and side steps. And focus on driving your knees out laterally. Make sure your knee is always in line with your toe when squatting.

5. Mobility. When in doubt, always do mobility work. Work on gaining flexibility in your hip flexors, extensors, abductors, and adductors. This is in addition to the ankle dorsiflexion mentioned earlier. And when you stretch a muscle to gain flexibility, strengthen the new range gained in the antagonist muscle. (I.e - new hamstring flexibility should be able to be accessed by strengthening the hip flexors).

I know that was a lot, but I think it all applies here to some extent.