I'll admit I haven't read this whole thread, but will just share my personal experience.

I tried individual therapy for years, and never got much out of it. When I switched to peer support groups (where the facilitator as well as all the group members have mental illness), I found they were much more effective. I really feel understood in support groups, and I enjoy listening to and helping others.

As far as affecting real changes in my life, the 12 steps are what did that for me. I did them as part of Overeaters Anonymous, but there are many programs that do them, including Emotions Anonymous, which is specifically for people with mental illness, whether or not they have an addiction.

I know this pandemic has made in person groups difficult, but there are may available online and free of cost.