Isolation vs Introversion

Is there a clear line between someone who is introverted and someone who is choosing to isolate themselves? When does “needing alone time to recharge” go from something normal to the extreme of isolation?

I feel that I have become a routine isolationist of sorts. By that I mean that for so long, especially during some very low times in the last few years, I didn’t want to be around most people because I was so deeply depressed. I had zero energy to spend on others because I used it all up trying to get by day to day. I needed that energy for basics functions as well as being able to work a full-time and part-time job.

So being alone became a routine. I would cancel on people, I would keep my free time open so I could truly rest.

Right now (knock on wood) my mental health is in pretty good condition. Things are going well at the moment so I hope that things stay that way for a while.

Since my mental health is fine, why can’t I break out of my isolationist routine?

Maybe it’s because I don’t have any close friends in my life. Maybe I’m turning into a hermit. Maybe I’ve lost my ability to be social.

I had the opportunity today to have lunch with a friend but canceled. I got a flat tire today so I said I couldn’t do lunch because of that even though my tire is fixed. I totally could have gone, but I chose not to.

My therapist encourages me to make friends and go out and do things but I find it very challenging to do when my comfort zone is so cozy.