How do people usually contact you, except the time when you had no phone?
Because in my circle of friends, we don't tend to send "how are you doing?" messages. We get to the point with whatever we need or want to do, or call right away for whatever other reasons.
I know how this can feel as I had people I considered friends to not seem that way, so in time I either left them, or told myself to take them more casually. Casualness greatly helps. Create more serious relationships with people who truly deserve it in your eyes.
Another thing I do is build strength of my own - I keep my hobbies and activities in check. To be honest, it makes me care less about whether others think about me or not. So long as I take care of myself and evolve independently, friends are merely an addition.

And are you treating your anxiety well? Such as exercising, diets, sleeping well, teas, meditation, etc?