Stuttering on words isn't such a big deal but blocking is an avoidance behavior. You said your biggest fear is it getting worse to the point where you can't speak to anyone. I advice is when you feel like blocking, try to stutter instead. That is, let go of the block and let yourself stutter the word out. As long as you move forward in your speech you will be able to communicate and people will still listen. Just you're right, blocking is an avoidance behavior you don't want to reinforce.