Why do stimulants calm me down instead of make me hyper?

When I drink coffee I don't ever get jittery or hyper I always feel more calm. The same goes for cigarettes and energy drinks. When I was younger I was diagnosed with ADD and was put on adderall and it did the same thing. Is the fact that stimulants calm me down because I am still ADD at 26. I thought ADD went away in your late teens.