Okay folks, I've got an annoying wardrobe malfunction going on and I don't know why. You see, the sleeves on every one of my shirts like to flare out wildly as opposed to hugging snugly to my arms like they should:

I'm paranoid that my shoulders are just too broad to fit into any girl shirts. My sister on the other hand says that it's because I have no breasts to fill the shirt out, and her evidence is in this second picture:

So does anyone have any advice? How can I stop my shirts from flailing outwards? Thanks in advance.