How could I be confident?

Hi, I’ve been in a lot of toxic relationships (past, family) and I literally don’t know what to do with myself now. It has damaged my self-esteem and confidence that I don’t know how to pick myself up. I’ve been depressed and anxious for 4 yrs, I’m turning 21 and I’m still the same. I’m confused and don’t know how to start. I want change and I want to be confident and improve myself, but how do I start?