You are like me. All those things you listed sound just like the problems I faced. I do have a therapist who taught me about mindfulness and breathing. Try out an app called Happier. There's a free yoga trial and it's really helped my anxiety so much.

Isn't it really hard to try and think positive thoughts about life and yourself when you've been basically thinking so negativity for so long? It's a big struggle for me to stop being so down about myself. Recently whenever I have thoughts that limit me or negative thoughts, I just catch myself and think "These are just thoughts. They are not true." And it helps me get out of that mental jail cell that I seem to lock myself into.
I wish you the best.