I'm 25 too.

I first sought help when I was 22, in the summer after I finished my undergraduate studies. I was Dx'ed with depression, ADHD, GAD, and OCD.

I thought the diagnoses were bullcrap, so I ignored them and carried on with my life until I hit 24. That was around the time I finished graduate school and first started working.

My concentration was always awful, but it seemed to be worse than usual. I didn't realize at the time that I was in a mixed state. That was when one of my good online friends suggested that I seek professional help, as I was suffering for such a long time and she said I really needed to do something about my depression.

Fast forward 3 months later. I was Dx'ed with bipolar disorder after my pdoc determined I was in a mixed state. (I was hallucinating, energetic, suicidal, getting 0 sleep, etc etc.) It took a non (pure) depressive episode for me to get diagnosed properly.

So in my case, it was pure luck. I happened to see a pdoc right in the midst of an episode. My therapist was (and still is) a complete moron. She is no longer my therapist, but she kept insisting that I had "never experienced depression before". Then she refused to read my mental health history, saying that she knew all there is to know. (If she read it, she would have seen the depression Dx.) So it goes to show that psychologists/therapists can't always be trusted to give the proper diagnoses. Sometimes they can't see what's in front of them.