I love figuring out décor details to bring out personality. Here are a couple of suggestions of what I might do if I was in your situation:
Think of the pastel pink as your neutral color. It’s like a big canvas that has a little more warmth than white. You just need to add accents to bring out your grown up personality. I would personally stick to one or two accent colors to keep everything looking put together.
Add some leather accents. Leather gives an instant grown up look to a room. Cognac color leather looks really pretty with pastel pink. Or if you want something a little more edgy go with black leather (or pleather). You could get a throw pillow for the bed or desk accessories.
Stay away from florals and lace. Florals and lace will always look kind of girly. Think about adding a bold contrasting color in the bedspread or curtains.
If you can add a rug, maybe you’d like a woven natural looking rug in a tan or brown or white if you want the room to look bigger.
Mirrors can add a lot of personality and make the room feel bigger too. If your parents are ok with you adding a big mirror, you can choose a cool shape and color.