Have you used a value scale when you work? It’s a tool that shows the range of values from white to black. It can help you see the values more easily in your work. There are lots of value scales online that you can print and use to help clarify values. Or you can draw your own. Hold the value scale in front of your work, squint your eyes and match the values in your work to the values on the scale. On what part of the scale are most of your values located? Are they all towards the center? Do you need to add values from either end of the scale?
Another useful tool is the value finder. It is a square of mid value grey with a hole in the middle. Hold it over your work over different colors. Is the color lighter or darker than the grey? The white value finder works the same but can be used for seeing and understanding lighter values.
Have you tried either of these tools? Do have trouble sorting out the value of colors in your work? If so, try one of these to see if it helps. Leave me a comment and let me know what tools you use to determine values.
Value scale and finder from toadhollowstudio.com