I know this has taken a really long time, but I finally have an update!

Last month, me and my Mum attended an assessment session near where we live - 18 months after finally getting the appointment. After an in-depth interview with a clinical psychologist, I have been diagnosed with Aspergers. I'm now waiting for the report from the psychologist, which should arrive some time in the next few weeks. He said that he's going to put "Aspergers/Autistic Spectrum Disorder" on it as the DSM changed to lump Aspergers in with ASD instead of having separate entries.

This was an enormous relief! I just wish it hadn't taken so long.