Do I have ADD? Please help?

When your mum says "it would've come up by now" she's actually got a point. You're born with ADD, and to receive a diagnosis, you must have had the symptoms from at the latest age 7. Sometimes and quite often, the symptoms are missed by professionals and never checked for. If this is the case, then you could well have it, as your description of yourself matches up with ADD. Psychiatrists will probably ask you for a self evaluation for now and when you were a kid, ask for old school reports and to ask your parents about how you where when you were a kid. In my case I got diagnosed at age 29 even though the symptoms were present at around two.