Judging by the trailer, you fight Laura before you fight Carmilla. Though we don't know for sure since Laura just says she won't show Gabriel where her mother is unless he's willing to "play" with her. And then those ugly fat dolls appear, so we don't know if we even get to fight Laura at that point, or later in the game. Or ever?
Also, Carmilla tells Gabriel that "There's no resurrection, only this living death you see before you!", so she's kind of helping him realise it's all a trap. Or something.
Also, there is that voice saying "Poor Carmilla, you will cry bloody tears before this night has ended" or something. Seems Carmilla plays a big part in this game, but is she 100% evil? Is she even on Dracula's side? (If Drac is in this game, that is..) On the other hand I think that big vampire with boobs could very well be Carmilla's second form.
Lol. Now THAT was some heavy speculation.