It's really personal preference, but I've always been under the impression that pointing the toes slightly outward is more stable? Again, I'm not saying that what you are currently doing is bad, but I think you're onto something that likely needs some correction to avoid the caving described above.
I would start by front squatting and back squatting with your toes pointed out.
I, personally, vary my stance from set to set because, to be frank, as I'm an absolute novice, I never land the same way twice. But one thing is constant - my toes are pointed out a bit. It's just the width or distance between my feet is a bit all over the place. I'm certain it will lesson with time and volume, but for now I vary my squat stances from set to set to compensate for my inability to be consistent - to be prepared for the inevitable, if you will?
All the best,
Lifting heavy stuff is fun and relative......