before looking at what anyone has said, and giving it a lot of though (I just got back from seeing it the second time) I think that I'm safe to say that Bella is an INFP, and that because of her "messed" up life, she isn't necessarily the cheery and affectionate INFP that we see a lot. I could be wrong, though..but I like to think of her as an INFP.
Now there has been some discussion towards Edward, and being an F or T. Hands down, he's an F. He is willing to risk his cover for her sake, and would risk his life for her, and you can totally see it in the movie and how much he cares for her, and what he tells her when they leave eachother. Now, I can see why people can see him as a T, because of how he tries to get her to stay away from him, disregarding his 'feelings' towards her..which is a T trait, but if you think deeply on it, you know he's an F..it takes time, but you will just know. Given that, I can see him as an INFJ. Which would then balance Bella and him out, giving them the perfect relationship that they have.