Thanks for posting!! Congrats on school! Mood boards are a great tool and lots of fun to get inspired for/by and make, but I can understand the trickiness of finding the right balance!
For color palettes, it is helpful to draw first from one or a few main inspiration images. When designing for clients for OMG We’re Coming Over, Breaking Beige, or other situations, I try to find the common color themes between the images they send me as inspiration for their rooms. Even if this exercise only gives you one main color, you can use Pinterest to look up lots of color palettes based on that color, see what fits the vibe you’re going for, and use that as a guide!
When deciding how much or how little to put in a room, I find that a floor plan really does help. Seeing everything mapped out, understanding the proportions and how each piece plays off the others. This will help you identify if there is too much packed in, or if there are empty spaces that could use a little more decorative love.