What GB to get for the iPhone?

I just got an iPhone 5s 32GB a couple days ago and already have 6GB in music. I only have 19GB left on my phone. Should i return the 32GB and get the 64GB or do you think 19GB will be enough.
P.S.
I don't take a lot of pictures, i mostly go on my phone to use Facebook, Instagram, and twitter and watch Youtube videos.

You should be fine, unless you also have a lot of video or take a lot of video. But if you can return it, then do it. It's only 100 more.

Well it depends on what you plan to use the phone for. So we of course wouldn't know how much you plan to use & for what.