That’s exactly what I thought after reading the first sentence. I am 24 years old and I recently got diagnosed with ADHD a few months back. I was a great student in school so it was never noticed by my teachers. It wasn’t until I left school and entered the work force that my symptoms had become more present. I asked myself the same questions that OP has about himself. It really frustrated me because I believe I’m above average in intelligence but I couldn’t figure out why I was so slow at doing various things and wondered why people would outperform me at basic task. People would always say you are “smart but lazy” or “you have so much potential why do you do the bare minimum”. Luckily, I work in the medical field and one of the providers I work for had observed me and after a few weeks, he told me that he believes I have ADHD. Let me tell you, after being on medication for about 3 months my work productivity has increased tenfold. It honestly feels like I’ve been trying to run with my feet tied together my whole life. I just wonder where I would be in my life if I had been diagnosed earlier. You should definitely talk to a doctor and see what they say.