I wonder if your records have been mixed up with someone else's with the same name. Yeeeees, that shouldn't happen, but in practice, GP support staff aren't always the best about filing.
It seems inexplicable otherwise that there's some sort of live CAMHS referral for you at your age, and that you're being diagnosed with trich when you say you don't pull.
It genuinely sounds like that stuff might relate to another patient. You can make a subject access request under the Data Protection Act to receive a copy of your medical records. You might want to think abut doing that so that you can see what is actually in there and what appears to be going on. You'd need to make one request to your GP, and another to the NHS trust that holds your hospital records.