Even if it's fake or she's not self-aware enough to get the right answer she'll grow out of it. She's 13, right? She could be a lot dumber.
Never liked the "how dare you self diagnose" stuff you see online. I bought into that when I was your age, and even though I obviously had ADD, I'd been medicated before and I was hurting myself, I decided I was fine because I didn't trust what I knew. I thought I just wanted attention and I didn't have the right to act like I was
really hurting, and I thought like that until I was 17 or 18. I don't know how common that is but that's my experience.
Also jesus christ diagnoses are expensive, I never knew til I came here but some people pay $500-1,000 to tell them what they were 90% sure about to begin with.
I'm obviously biased but I think the internet makes fakers look more common than they are, at least for common stuff like ADHD. Once they decide they wanna make fun of some group they'll see them everywhere cause it gives them more chances. Besides, half the people here are self-diagnosed.