White is a cool color but if you have a white space that you're looking to warm up I'd suggest bringing in some neutral or warm hues to the room as well as lots of texture such as corduroy, faux fur, and velvet. Imagine changing out the black accessories in the rooms shown above for rich brown tones. Add drapes over the current sheers which can add both function (literally keeping the room warmer) and style, a couple of toss pillows, and a throw (which is also functional for snuggling) and you've got an instant Winter Wonderland!
Look at your white room as a blank canvas. The bedroom shown above has endless style possibilities. I can imagine it transitioning perfectly with just a change of accessories from season to season making the space suitable year round.
In spite of everything I've said remember your space is your own, and it's meant to make you happy, so if you're comfortable with your all white space...Don't change a thing!