I agree with what your saying about Adults not being able to get the help they need. Healthcare professionals seem to not realize that these babies and kids will be adults some day and there will be not help for them.
I did find a site called pkuchallenge.org it is geared for adults with PKU. The founder is Chris Howell. He is looking for adults with pku and from what I read he tries to help PKUers to get formula until their insurance kicks in. Just a suggestion. Hope this helps.