So I just got my first binder

It's an Underworks 988 XS.
Minor Problem: I have a small chest, AA, I think, but anyways, I put on the binder, and it still looks like a uni-boob, or is it just me? I think the dip right after my breasts sort of gives it away... Any advice? I'm planning on exercising a bit, loosing the bit of tummy I have so fabric doesn't cling to that dip, but, am I putting it on wrong or something? I heard I should push my chest a bit to the sides, that seems to improve things... I don't know, I have rebellious perky breasts

Major Problem: The back of the binder sticks out when I raise my arm or put my arms back. It sticks out like a triangle near my neck... Anybody have this problem? Anyway to fix it? After I'm sure the binder is comfortable I was planning on sewing it a bit smaller in the back, or maybe cutting out the harder fabric beneath just a bit. Maybe I could safety pin it down for now... Anyways, it looks really weird. Sadly I don't have a camera to show you just how much. i would think this would be caused by the binder being too big, but it's already and XS and it fits just right everywhere else.
Edit: Oops, should I have put this in the FTM Gear part of the forum, sorry... still a bit new here...