You are so right about all the mediums, with the one exception of #5.
The easiest way to find "some darks" and even some lights in this case, might be to take small snips of the colors in your fabrics to Lowes or Home Depot and visit the paint department. Use the chip cards to match your colors and then note the colors (plural!) on the cards that are above and below YOUR colors. These cards are free and you can take a few home with you.
Remember that pink is a value of red. There is a very pale pink and a quite dark deep rose. The same holds true with your green. Once you begin laying your fabric beside other values of your chosen colors you will begin to see how you can add more if you wish.
I urge you to "just do it"! It will help you with projects to come as well.
And, if all else fails, google "green and rose (or pink) quilts" for some ideas.
https://www.google.com/search?safe=a...30.Ek83iokrI3c
Good luck, you've got this!!
Jan in VA