Retaining knowledge

I’ve always been a really great student and always get top grades. But I don’t. Retain. Knowledge. Other people struggle so much in college classes, while I get the material immediately and kill it on exams and assignments. I'm talking 100s on exams that made everyone else cry. But then if you ask me about what I remember a year later, the answer is absolutely nothing. Even people who barely passed the class might know more than me.

I could read a whole nonfiction book, something that I CHOSE and wanted to read—I might accidentally skim over things and have to reread a paragraph several times, but generally I do get the material. Until I finish the book, or even just the chapter, and it’s out of my head as though I never read it.

I’m undiagnosed but definitely neurodivergent in some way. My family and I always knew since I was a kid that I was autistic, but diagnostic testing was not "worth" the money since my neurodivergence didn't hurt my grades the way my sister's did. So I only knew myself as autistic, and I was honestly shocked when my new therapist (who has ADHD) told me she was 100% sure I have ADHD. I couldn't believe that she was even more sure of that than my autism. Even my previous therapist, who evidently knew nothing about AuDHD, had told me something along the lines of "I don't think you're autistic, because you can socialize. If anything you're ADHD, but you get good grades so I don't think you're ADHD either."

Before now, it had never occurred to me or anyone around me that I could have ADHD. I guess because I was such a superstar in school and again there's that stereotype that ADHD = poor grades. Especially next to my very ADHD sister, no one thought to look at me as ADHD because I was so different from her (and I was so obviously autistic, and you can't have both right?). But now I've read up on AuDHD and it honestly fits me better than autism alone. I'd like to eventually get a diagnosis and see if medication is right for me. Until then...I don't know. I hear caffeine helps with ADHD a little? I don't like coffee though.

So anyway, are these memory retention issues common with AuDHD? Do stimulants help with memory and learning? What do I do? I’m sick of putting in so much effort and getting nothing out of it. I don’t even remember facts about myself! I’ve had to make lists of my favorite books and movies so that I don’t forget what they are. Now that I'm an adult, I'm starting to realize that this is really not normal. I'd just like to be able to trust myself to know things.