Somedays I feel like I am focused as ever and could take on the world, organizing it one bit at a time. Other days like today (which are rare) I feel like I can't stay on one topic, or switching to being productive is hard. Other days when this has happened I take a step back and shower or take a nap to refocus, but I was wondering if there is a type of food or vitamin that would help with this.

Also... could this be a sign my dose needs to be increased?
I'm on 25XR. I'm 5'2 and 132lbs.

(I've lost 45 lbs and my doctor is happy as pie even though that wasn't the intention. My asthma and health problems practically don't exist anymore, haha)

I think it's a mistake to see an occasional "off" day as a sign that your dosage isn't working. If it weren't working I think you'd notice that on most, if not all, days.

I wrote a post about this on another thread recently (can't remember which one, sorry) but the gist of it was that we all need time to recharge our batteries, mental and physical. The drugs can't make that fact go away.

Even on Adderall, I sometimes have days where I'm just not focused/energetic enough to be productive. What I've found is that on those days, it's better not to fight it, just do what you absolutely HAVE to, and spend the rest of the time doing things you enjoy.