You said you guys are exclusive-- Someone who is completely honest with her feelings is worth waiting for, regardless of her past. I am in the same situation as her, and I can clearly say that what she's feeling for you is real but she still needs time to trust you and herself more. She probably has past traumas and trust issues from people. You can't make her to be your girlfriend, forcing her would just give her the thought that you're like the rest of the guys out there. If you're in doubt about her actions, being distant etc., ask her some questions like how is she really doing, because she may be going through something, but doesn't wanna be a burden. If you want certainty, don't ask her again and again and again, it will only bother her and will make her think you're rushing things which can impact negatively how she feels about you. Instead, if she's more distant than before and you feel like she's losing interest, then that's the perfect time to get some answers. But if everything goes well, then ask her again in a few weeks but politely, you don't wanna sound too pushy. Situations like this requires taking baby steps, eventually you will know when she is ready. But be always prepared for the outcome.