Then I realized I'm constantly tapping the floor with my feet as I type
That's restless leg syndrome, a lot of people do this.
ADHD really isn't real in a disorder sense. It's a label given to people who fall within a range of behavior that is described as hyper and inattentive. Normally this wouldn't matter treatment wise, but the label is used to get kids to take amphetamines and stimulants to stay focused, which is bad.
The entire coming generation is going to have issues with attention. My guess is that it's due to the way our society is now, where everyone seems to always be on the go. Not only that, but the newer generations are in a time where they are bombarded with information, and have limitless access to it via the internet. Couple this with the increase usage of video games for teaching, entertainment, etc. and how accessible they can be, such as through phones and other portable devices, and it's no wonder that the younger generations have horrible attention spans.
