Well, the good news is that you can definitely do more to be yourself, and the tools here can help extensively.
Unfortunately, you will never be able to simply “not care what others think of me.”
As in, its biologically impossible.
It’s an inbuilt survival mechanism and occupies a very primal part of your brain.
There are several studies on it, but this one is the easiest to read: Why You Should Stop Caring What Other People Think
I caution you against having people not care about you as a goal as quite a few people here decided to do just that (including me for some time) with little to no research on the subject.
You can definitely turn down the volume of these thoughts, have them come less and less, but even superstar performers, olympic athletes and successful businessmen struggle with it. Even @El_Capitan_Nemo has had times where the negative criticism of others has gotten to him, and this is not a diss. Theoretically he should have all the tools to combat this, right?
You’re not broken, you’re just human.
In my mind confidence is about overcoming learned helplessness and the comfort of a consistent prediction, which feels comfortable. Knowing, or thinking you know what will happen, helps prevent future pain. Its how we were built to survive in ancient times.
When people talk about being confident what they are really talking about is overcoming learned helplessness. LH is when the brain enters a condition where there is no thought about doing anything. Just reaction to situations.