A long time ago I ordered a foundation from QVC from a rep who claimed that his foundation would cover everyone from the lightest to the darkest. I couldn't understand how, but ok, I ordered it and when I applied it I look like I had been dragged face first through the dirt~! Absolutely didn't match, didn't even look like I had a tan.... I simply looked really dirty.
Finding a match (or developing one as the OP has done) is imperative. I'm not that light, but light enough to have trouble wit most foundations out there, if it's not too dark, it's too yellow! I've finally found one that's perfect..... finally.... and they better not discontinue it!
*~"Never eat more than you can lift......" Miss Piggy~*