How to be more confident?

And I don’t mean in just looks, I mean everywhere. Self esteem etc.

I’m tired of constantly comparing myself to everyone and I’m tired of constantly feeling threatened by the presence of other people.

I’ve been on this journey to self love and acceptance but it’s proven to be difficult.
I’m aware that other people may not see me the way I see myself but that’s easier saying than it is believing.

My brother told me “I don’t think other people see you the same way that you pick yourself apart. But You kinda hold yourself pretty confidently anyway.”

It’s interesting that he said that because I didn’t think I held myself like that in any way at all. But maybe I am improving slowly but surely.

My main thing is how I look and also finding/accepting love from others.

When I look I’m the mirror I see a big ugly monster.

When I have a group of friends I start freaking out about the littlest things and I start believing that they hate me.

It’s a cycle that I’m noticing and Have been trying to break since the beginning of high school.

I’m really trying to combat these thoughts with positive ones but it’s difficult. Does anyone have any suggestions as far as cognitive practice?

And please no “maybe you need to hit the gym.” I already know this and my mental/physical health is something I’m currently working on.