I Hate Paint

My living room needs help. I thought I could save the day, but I can't. It needs paint. Someone who is daring, smart, with x-ray vision. I now have 3 gallons of paint in my possession, from 2 different stores, and they are all the exact same shade. I wanted something light brown, not white--heavens no. So, I picked one out, bought 2 gallons at Wal-mart. I spent all day priming the wood walls with white paint. When the moment came to finally add color, I couldn't see the difference between my "brown" and the white primer. Rats! So, the next day we made a trip to Reno. I stopped into the Home Depot. This time I decided to go for green. Calming green. I found a shade, the man mixed it, then dabbed some on the top.
"This will darken, right?"
"Of course."
Not.
I spread it on the walls as soon as we got home, I was so nervous. It was amazingly the exact same color. I was even going for daring this time! I literally sat down and wanted to cry.
So, when I say I need help, it's true. Someone please explain to me how in the world stupid paint works. Maybe it's like the "Emperor's New Clothes" and I'm supposed to just pretend it's the color I want. Whatever it is, I think I have the Midas touch, only everything I touch doesn't turn to gold--it turns to off-white. Ack!