The window is super tiny and it's not letting me expand it, it's pretty hard to see stuff in the game.

Yo!, normally if it does that, try to press F1 while ingame and it should open a settings menu to allow you to go Fullscreen!

Edit: Hint tho, you have to restart the game after you check the box!

I use this app to make the window bigger, as Fullscreen distorts too much the game:

http://www.airesoft.co.uk/windowwatcher