last to first - St Johns wort. Proper exercise.
For energy - work on rejuvenating and virilizing yourself. I will leave you to do the research.
For a quick fix, ginseng is really really good, I would also recommend ephedra(if you use ephedra in a Red white & blue you come out with 3 types of amphetamine - this should tell you a lil bit about how powerful it is as a herb).
I personally just use bananas, mangoes, ginseng, and guarana, but I wouldn't suggest guarana if caffeine doesn't agree with you... It contains twice as much as coffee beans do, the buzz is more euphoric though, doesn't make me feel tweaked in the same way at all.
Yerba Mate tea is slow release - but also caffeine - I like it though - I use it to go raving or hiking.
You need to tonify your adrenal system, not add more stimulants.
The #1 herb for this is rhodiola. You can buy it at any health food store. Make sure each cap contains at least 200mg of the herb. You'll take 2 each morning before breakfast, and that's it. The effect is cumulative and builds over time. It's an adrenal adaptogen so it will restore your "awakeness" levels during the day (particularly epinephrine supply) while managing cortisol levels that result from stress. During the day you'll have more endurance but at night it will kill cortisol so you can wind down. It's natural and safe for the long term - I'm currently taking it.
Once it kicks in you'll notice you need caffeine less and less to get by, and stress will not affect you as much. Caffeine artificially extends the adrenal system. Rhodiola strengthens the adrenals so that they can provide natural endurance.
Good luck.
Nice one! I like this advice...I'll check that stuff out myself...even though I don't drink much caffeinated drinks at all, I'm sure boosting my adrenal system can't hurt.
To be honest though I wouldn't do ANY stimulants if you've got this sensitive to caffeine - sounds like your body can't handle any right now, plenty of warm milk for you! Calm you down, stop you getting emaciated!