i know I’m not mr. Kate (sorry 😂😬) but I think I can help you. Your room seems small, like mine, and I am re decoration too so here are some of the things I think:
-try painting ur furniture ( like ur bed and dresser ) pale colors (white, light pink…) and adding accent accessories (lamps, trinkets) that u can paint as well
-take this opportunity to go through ur junk and sort out what u really want to keep and donate/throw away the rest
-definitely check out flea markets and thrift stores (research them first becuase some just sell clothes or jewelry and that wouldn’t be what u are looking for)
-diy ur own wall art. Like this u can have the exact look your going for
i hope it was helpful!