The worst case I ever saw was a couple who'd spent over $750 in sample quarts from Home Depot. They did the very thing that confuses people the most: painted out weak patches of a multitude of colors on one wall:
I NEVER recommend buying sample quarts until AFTER some FREE experimentation has occurred using the paper samples provided by the paint store already. These are found in the color chip area and you can take several of the same color, cut the tiny square out (in multiple quantities) until you have at least 6-8 of these, and tape them together to create a larger patch. You can then put this up on your wall and move it around the area, look at it in the dark and the light, around your art work, close to the cabinets, etc.
Once you've gotten as close as you think with the right color, you are ready to buy a sample. Benjamin Moore now has pint sized samples (in an eggshell finish only), and these cost about $8.00 each. Spend another $5.00 at an art store for a piece of foam core board that's about 3' x 3' in size and then double coat a side with your sample color. Now hold that up and see what this larger sample looks like- again- without putting ANY paint on your walls.
This process of being patient and deliberate should inform you right away about your chosen color. If you still are having issues- HIRE AN EXPERT! Waste no more time & money.