I am 18 years old male, Do I have ADHD?

Hi, I am 18 years old male. I randomly came across the website about ADHD. My symptoms fit. When people are given instructions, I find it difficult to follow them, I have to read them and long time to process them. But I am a quick learner but when it comes to instructions, I go blank for odd reason. My body reactions are slow, such as when my friends and I play some reaction game, I come last. I frequently ignore when people talk to me unconsciously, like staring at a wall, more frequent than normal people. I find it difficult to stay on one topic for alot of minute, I always end up moving to different topic. I am not patient. I have low concentration. I get distracted very easily. Right now, I want to go watch youtube videos. Everytime I turn on my computer, at the time I shut down my computer, there's multiple amount of windows, around 15? I always try and find a shortcut to instructions that I am given. I try to avoid obeying the laws. I find it difficult to start and finish assessments. But I manage to do it somehow... Anyways. These symptoms really fit ADHD, Please tell me, do I have ADHD? is it curable? I hate losing concentration and losing interest, it's uncontrollable.