That sounds like me, usually. Forgetting what I'm doing, where I'm going, what I meant to get... Of course it's either that or complete hyperfocus.

I use extensive lists to keep myself on track. It doesn't always work--like right now, I'm off track by three hours because I got a phone call I wasn't expecting.
But stimulants don't work on me--I'm predominantly inattentive type, and apparently that's common.
Caffeine helps a little, but I get withdrawal headaches if I use it too much.

I am inattentive. but the ADHD meds work on me. at least adderall does. ritalin gives me a bit of irritability, mood changes, and paranoia.