I don't know about ADD, but I know I've honestly never had much of an attention span. I either hyper focus or don't focus at all

I'm not sure if much of what I can say would really apply, since I work one of those low pay high stress jobs.
My partner is an artist and she struggles with focusing too. Give her too many tasks and she'll shut down and nothing gets done.

For me though when I can't focus (as my mind is a racehorse of voices in my head), I tend to drown out all the other inputs with music. They're just my inner thoughts that need to "sit down and shut up" so I can focus. With the loud music it seems to allow me to only be able to focus on one thing at a time.

As for why she took you off the meds. It's possible the one you were on was backordered (pharmacy can't get it). When someone hasn't filled adderall or similar for a while pharmacists get hesitant to start filling it again.