What causes memory to degrade suddenly in a 18-year-old?

Hello doctor,

I am an 18-year-old female who has for the past months been experiencing that my memory is degrading badly. I have always had a memory that was fair enough. I do have much stress and I do have social anxiety. I do not sleep that well, but that was never a problem before. I sleep around, 6-7 hours on school week. And 9+ hours on a holiday. I do take some medications for my ADHD and I am aware there are some side effects to that medicine. I could not even remember, a friend's name that I recently met, for some split seconds. Then after some thinking, I could finally remember it. I can remember certain situations that were very important. I could remember something from 5 years ago but not 2 weeks ago. And I do feel like, my memory gets better after I eat food. But it feels like it is getting worse as time passes. I did as a child had to do mind memory games at school, but I felt like I could still remember basic information or situations that happened some days prior. But now, I cannot even remember what I did 3 days ago? Is there something wrong with me? I am showing early signs of dementia? Or I am just overreacting?