But she HAS found her place 'in all of this' and that's a place of being the last Jedi and helping the Resistance, her friends, beat the First Order. She had no place before, she didn't know what she had to do or who she was, she felt that talking to Luke would give her this answer. That Luke would say, "you're my daughter! And as Luke's daughter now you fit into this peg" but she didn't find those answers from others, she had to find her own answers. At the end of the movie Kylo Ren tells her she has no place in this story, that she's no one, but she rejects that notion because she HAS found her place in all of this and she didn't need Luke or Kylo to give it to her and she didn't need to by being anyone's kid. She found it by herself.
I'm not sure I get where you're getting this idea, honestly. In TLJ we get a new concept, that the cosmic Force awakens Rey's powers to go against Kylo Ren. The Force does this to directly fight and beat Kylo, no? Then wouldn't this stand to reason that the balance here isn't about having 1 Lightside user and 1 Darkside user but having something to counter and beat the darkside user?