I would chalk up some of the anxiety to "This is getting waaaay too real" syndrome. Seeing a therapist, addressing your GD, and actually doing something about it is no longer a "Some day" abstraction. It is happening, for real, tomorrow (if you don't chicken out)
Knowing you have GD is easy. You know it. Now what? Where on the spectrum are you? Where are you comfortable going, today? These and many other questions you will explore. It isn't an easy thing to do alone.