you are a fascinating case; all your tunnel experience should put you in a great spot to be able to do it on your own. 20 hrs in a tunnel should make you at ease in the air and be able to overcome the normal worries of new skydivers, like becoming unstable or failing to be able to follow the dive plan.
i had a lot of fear as a newb, but it was rooted in those types of fears, getting stuck on my back or in a spin or some such. You don't seem to have those sorts of fears, and the solution to those would be to tell the scared student to "go spend some time in a tunnel" :) of course that won't work for you.
so I dunno. maybe talk to a professional / therapist about your fears? or put it down for a while.
