For similar reasons to your use of caffeine, I decided to intermittently take Sudafed for when I needed extra focus or energy. Not the off-the-shelf kind with phelylephrine(which is a total placebo), but the kind with pseudoephedrine that you have to ask the pharmacist for. I find it works very well for short periods of time, and it has effects that are closer to that of prescription amphetamines. I'm probably on a list of "possible meth cooks" at this point because of how often I buy it, but it's worth it to not have to justify myself to a doctor all the time.