How can you tell if a teenage girl has ADD and what are the symptoms?

I am a teenage girl and I have ADD. I was diagnosed this summer. My symptoms may be slightly different then yours but I was really disorganized because I couldn't focus on that one thing and it frustrated me so I moved to the next thing. I couldn't focus on one thing for a long period of time because so many other things caught my attention (My attention span is around 5-10 minutes give or take) I got frustrated and I had very frequent mood swings. I tended to annoy my friends by one minute being nice and the next not wanting to talk to them. I was really fidgety and I like doing activities because I can focus more when I am not sitting down (this is part of ADHD), I didn't let people finish what they were saying and I blurted out all the time. I couldn't follow instructions and either missed out a part or thought it was one way rather than another. Most of the time I left whatever I was doing unfinished. I interrupted people. I didn't listen. I didn't pay attention to details. I made careless mistakes in schoolwork. I lost things and forgot to bring things in to school, or forgot to finish them, or even do them (usually purposely but not because I didn't want to, just because I COULDN'T) I had many things floating around in my mind, and couldn't focus fully on any one of them, like I was only half there.

I am now on meds but some of these things still occur, just less so than before.