You’ve put the cart before horse, you cannot take the medicine to get a diagnosis. There are different medications that work for different people at different doses, you don’t just need a psych for the prescription but also to manage how you take it. Try taking an online screening test. If you score highly then consider reading over teacher notes on your school reports and/or discussing it with someone very close that you trust will take the conversation seriously to see if there are ADHD indicators noticed by others. I’m not sure what your history is and I’m not going to push you to anything you don’t want to do. But I also don’t want to walk past someone who might be dismissing something that could be very beneficial for them based on some DIY that is not representative of what professional help can do. I wish you the best whatever you decide to do.