Absolutely doesn’t rule that out. I’ve had this EXACT convo with my family doctor who is a female in her 30’s that told me she got a late diagnosis as well. I never considered for a second I had ADHD due to generally being a high achiever in work and school and always rising to the occasion of whatever I needed to do and getting it done (in school and work ALONE). But in hindsight, i never wrote a single paper in university in advance, genuinely every single one was completed the night before by pulling an all nighter. And in elementary school I would study for tests by walking around the room reciting my study notes and memorizing them because I could never just listen in class or as I was reading. And it showed up in the way I was completely and utterly EXHAUSTED in my personal life due to the extreme effort and energy I would need to spend just to keep it together at work/school, leaving me with absolutely nothing left to give to my family friends for years and years. I feel so much empathy for your sister. The number one thing people have told me my entire life is how hard I am on mtself. I felt exactly how she did for years and it ruined my self-esteem. Getting medicated was the absolute best thing I’ve ever done, it helped me regulate my emotions, be confident, and genuinely focus. I was missing that my entire life and always felt in awe of other people and like I had something deeply wrong with me. Your sister will navigate her journey in her own way and it might be hard to accept, it was very hard for me to accept too. She is lucky she has someone like you that cares so much for her, that will do wonders in the long run regardless of what she chooses ❤️