Yeah, you're probably right. Tea and coffee contain many substances and all probably have an effect in one way or another.
For whatever reason, dopaminergic herbs work better than potent dopaminergic medications for me. Maca, Rhodiola, and Cordyceps all have a noticable beneficial effect with little to no side effects, aside from that annoying puffy nipple problem. Methylphenidate, on the other hand, just doesn't feel right, it feels like I'm on a drug when I take it, but with the herbs I feel normal. It also doesn't work nearly as well as the herbs and has lots of side effects.
The only good drug that doesn't have any side effects for me is Modafinil.