UK psychiatrist experience with treatment resistant ADHD — oral medications actively counterproductive, looking for someone who can go beyond standard titration

I’ve been diagnosed with severe combined ADHD (9/9 inattention, 6/9 hyperactivity) through private assessment and have been through titration on four different medications — modafinil, lisdexamfetamine, methylphenidate, and dexamfetamine. All four have followed the same pattern: a response on first or early exposure, then complete collapse of the dopamine component on subsequent doses regardless of dose increases, leaving me worse off than unmedicated baseline. Fast metabolism appears to be defeating oral delivery across the board.

I’ve done the research and I have a specific hypothesis about what’s happening. What I’m looking for is a recommendation for a UK psychiatrist who has genuine experience with treatment resistant ADHD and is willing to go beyond standard oral titration. Ideally someone with knowledge of named patient prescribing or alternative delivery mechanisms.

Has anyone found a specialist who actually engaged with a complex case like this rather than just cycling through the standard formulary? Any recommendations, even indirect ones, would be really useful. Thanks!