If you can live your life normally without drugs, and interact with your family normally, and nobody would know you had a problem; what benefits would an official diagnosis achieve ?
However; If you cannot concentrate for long periods, cannot drive a car for example, or cannot sit still or cannot listen or follow complex instructions - and calmly remember and perform complex actions, that would prevent you becoming a pilot.
If you cannot take the initiative and solve complex problems or situations by yourself, and cannot study intensely under your own initiative; ditto. Pilots tend not to be spoon fed - they have to work a lot of stuff out for themselves.
Normally we advise getting your Class 1 medical before spending any money on training; but I would suggest paying to go through some courses of psychometric testing to see if you might be able to pass an airline assessment - before spending lots of money on ATPL training.