CHICAGO — Midway through her graduate nursing program, Yesenia Raithel Vargas made a desperate plea to a Facebook group for other moms in Chicago: Does anyone know a licensed therapist willing to let her sit in on sessions and work with their clients under their supervision? It was a strange ask in the therapy world, which is one reason Raithel Vargas had resorted to Facebook. “I must have sent 50 emails, or made phone calls, just trying to figu…