The fear of being alone was stimulated by your move away from your family. Moving is a big change in a person's life even if it is a planned move and a good move (new house, better job, school, etc).

It is very much like agoraphobia, because "home" in this case is defined by being near your family. Being near your family feels comfortable, familiar, safe. So, instead of being unwilling, unable to leave home, you are unable to leave your family. It doesn't feel good, it doesn't feel safe.

It is a kind of separation anxiety and a therapist can help you explore what's going on that's making you feel this way and to help you find relief so you can feel much better and do the things you want to do.