Feel irrelevant and outdated?

Okay I’m really bad at explaining things but I’ll give it a go. Basically, when I was 15, I visited a psychiatrist and was given a diagnosis(which I don’t really want to go in to), I had CBT which didn’t work and have never tried medication.

Now that I’m 20, nearly 21, I know this may be stupid to think and say but I almost feel as if my diagnosis is outdated and irrelevant now, I still suffer greatly with my mental health, if anything, gotten worse, but it’s strange, I feel that my diagnosis is old and irrelevant because it was nearly 6 years ago.

Anyone else ever feel or have thought this? I don’t know why but I feel like it’s really silly but I can’t help but feel like I don’t deserve to feel the way I do etc because I feel that it was a long time ago when I saw someone🤷🏻‍♀️