As
@mikew showed, you are close. Very many of my macro shots come out dark, so much so that I cannot see them on the camera's lcd. As with most captures, it will require some post processing to get it where you like it.
The starting point (triangle settings) that [MENTION=9753]Scott Murray[/MENTION] suggested is going to be pretty close and you shouldn't have to go very far from any of those. Of course this statement is given without ever seeing a flash ring and/or light ring in person. I have tried a hotshoe mounted flash and was not totally satisfied there, the truth is in my opinion, the popup works very well with the correct diffuser setup. The below image is with the popup and home rigged diffuser.
