I have two suggestions. Well, three! Your dark curtains chop up your wall space. If you replace them with curtains that are close to the wall color your space will appear lighter and more spacious. The second suggestions is to edit your accessories. I'd take down all your wall decor and only put back the things that you love. Right now your walls are too busy and cluttered. The third suggestion is that when you re-hang your favorite things, hang them a little lower. Right now your wall decor is hung too high.

If you could post some more pics with daylight and open curtains you might get more suggestions. It's hard to see the details in your photos.