How can I fix this uv unwrapping issue? So I tried making this human model from a tutorial, but when I try to texture it, the uv mapping is acting all weird. The chest area is really disproportionate from the rest of the body:

When I tell blender to unwrap everything, it makes the upper body tiles really small for some reason:

I probably just need to add some seams here an there, but I can't quite put my finger around it. How do I fix this?
Here's the blend:
http://pasteall.org/blend/index.php?id=50207
There are not enough seam cuts, you really have to think like you're cutting the shirt with scissors, otherwise Blender can't properly unfold the mesh. If you add some additional seams on the shoulder and on the sides it will map properly.