ADHD or Generalized Anxiety Disorder?

I have Generalized Anxiety Disorder, and some form of depression, but I m convinced that there is something more than that! Especially when I have symptoms of short term memory loss, drowsiness and concentration problems. For me they happen when for example I'm going for long holidays and have a lot of things to do, prepare etc.I have lots of college assignments to do etc. I believe that I'm not good at organizing and multitasking. And I always had a problem with maths! So my main question is if I would have ADHD would my mentioned problems fluctuate or would be always like that?Or this is really my GAD who is making me to believe and feel that I m having ADHD?I allways google and the googling makes me worse, it makes me think that I have bipolar 2, ADHD etc etc.. I m also hypochondriac..