I would avoid young ML as they might be confused and react unaccordingly.
I am sure that most of ML with extended experience in this industry wouldn't be surprised as I am sure they have dealt with a lot of punters with erectile dysfunctions for many reasons.

Renwick body massage has many girls specialising in prostate massage and dragon tendon. Even though it might not be recommended for you, they have probably more knowledge about sexual anatomy and could be more attentive to your concerns.