Do I have ADHD or something?

I'm 16 and I'm really starting to believe that I might have ADHD. First off, I interrupt others all the time without even realizing it. Recently, my friends have told me that I always interrupt while others are speaking. I honestly never knew that I did that until I acknowledged it myself and found out that I really did. Secondly, focusing especially in school is very difficult. I can't focus at all to what my teacher is saying no matter how much I try and try to focus...it actually gets pretty frustrating. For tests, I probably have to read the question 5 times until I know what the question is asking because I can't focus...I'm thinking about other things(unintentionally). Also, my mind is constantly thinking about everything and anything which makes me emotional easily. I'm always thinking about what I do wrong in my life, I definitely get insecure very easily. Another example is when I play sports....my coach is always telling me that I need to slow down and to quit thinking about everything while I'm playing. When I play games, people always tell me im doing too much and that I need to slow/calm down...but its hard. I'm just tired of how I'm acting because now I do realize I do way too many things at once but I'm always trying to motivate myself which fails oftenly. I just want to know how I can adapt to my mind so that I can live my life the way I want to....thinking honestly gets the best of me. I apologize for the long post...guess I wanted to rant too. What do you think?