I think you won something valuable with this girl right at the get-go...she saw that you are sincere, and that she can talk to you without fear...as far as she is ready to go.
If this is true, it's a sign that both of you are well into a friendship.
I say, "Congratulations...both of you!"
In my world, it is important to know, hear, when you have done something well...even if it is only the beginning.
I hear that you feel under-qualified to do the job you are doing with her...but, what if you are a natural? At the very least, a natural with this girl, the perfect person to help her?
Winging it, sensing the right thing to say when the moment arises, going with the flow, disclosing that you, too, have had an experience...and that disclosure being 'okay' with her...may mean that you ARE qualified...emminently qualified.
You certainly have proven yourself, and she has risen to the occasion, too.
Maybe such a perfect opportunity will not happen again to either of you for a long time...or maybe you both are naturals, ready, and further along than either of you thought you could be.