Overall ... I like the grapefruit/orange and grey combination. Not crazy about the single yellow, I have two thoughts on that. One is that it's too bright and "primary" compared to all the other toned down secondary colors. I would choose a yellow that is a little more muted to compliment the other color palette. The other thought is that is "lonely". Adding one more fabric perhaps a grey with yellow print would round the pallete out nicely.
With regard to the fabric choices, they kind of scare me
The texture would be awesome - the mix of cottons and satins and flannels ... but I would worry about how they will behave together to be sewn and laundered. If you pre-washed - great - if not - I think you are going to have a very bad surprise. Also, with the satin and the flannel you really should use a larger seam allowance because they both fray a lot - but as you've already cut them (and presumably to the same size) your next option would be to stay stitch around the edge of all of the squares. Ugh.
Good luck, the color pallete is lovely!!