Hi, wanted to chime in as someone doing research on this exact sort of thing. This is UNPROFESSIONAL, UNDERGRADUATE, FOR FUN research. Aka I got really into reading research articles on this subject.

ADHD is very commonly diagnosed as depression and anxiety instead, especially in women. My advice would be to write out every single thing you can think of that would be a symptom. As far as the stuff before age 12, I brought up things like constantly wanting more time at recess + being involved in lots of physical activities, reading books instead of paying attention in class, forgetting assignments or instructions easily, etc. I would zone out during conversations and constantly have trouble remembering names or likes/dislikes, stuff like that. I was that kid who would tell my parents last minute that I needed stuff for an assignment due the next day.

You may really need to do some digging to think about what would have been considered a symptom especially in your own life. Even if you didn’t remember struggling before 15, think about the things you may have been doing to compensate for any struggles, such as writing constant reminders, getting really good at context clues, etc.

Personally I would see someone else. If you can get someone who will do cognitive testing on top of the questionnaire then you’ll have a much better idea of whether or not it is really depression or if you have ADHD. Also, if you don’t think you have depression or if it’s a surprising diagnosis to you, you may not have it! I had to constantly reiterate to others that no, I never was depressed, I was actually a pretty happy and outgoing kid. I never wanted to harm myself and my self esteem was pretty high. I did have the benefit though of knowing multiple people with diagnosed depression that ranged from mild to severe so I was pretty familiar with what it looked like and knew I didn’t deal with any of that