Does anyone have any good over the counter stuff they combine with their prescription for a better effect?

I'm taking fish oil, vitamin b-complex, magnesium, and calcium

But I'm thinking maybe adding caffeine or a nicotine patch (not every day!) or something might work good for periods that require a lot of concentration.

Antioxidants to counter oxidative stress from dopamine. Several things are mentioned in studies. R-alpha lipoic acid (RALA)for example can cross the blood brain barrier. Interesting vitamin C can not cross the blood brain barrier but oxidized vitamin C can and is regenerated to vitamin C in the brain with RALA. The doses of antioxidants in studies are quite high but the doses of stimulants were insanely high to so reasonable doses of antioxidants might be useful in typical stimulant use.

You mention caffeine and nicotine they might increase the vasocontriction and
send your blood pressure up so check that out. And opposite approach of using
a vasodilator like vinpocetine might increase blood flow to your brain. I think
some studies have suggest a small increase in temperature in the brain can
have negative cognitive effects and /or neurotoxic effects. A vasodilator might
help keep your brain cooler.

I know some people take Levodopa/LDOPA to help out with dopamine levels.

Yea. Except there is a nausea side effect that's common with LDOPA. I know there's something (aside taking it with meals) that can be done to help with that...