welcome to beyond blue.
Firstly, let me say that I take medication for depression. And for those who I feel comfortable with, when they ask me how I am I will say something like "neither up nor down, just existing...". I say that because when I cannot say that I feel good because that feels like a lie. But I cannot say bad, because that would be a lie also. So what your BF says is probably close to the truth. On the other side, I have a fair idea of how I would be without the medication so it is better that I do.
It is also good that you want to learn more, and support your BF. The best place to start would be here...
I hope you find the above pages (/documents) useful and hear more from you.