A part of her wanted to write to Sirius and ask if he knew anything more about her, and another part wasn't sure she wanted to know. Professor Dumbledore had made it as clear to her as possible that she was Bella's only resort. Hermione was smart enough to know that the reason for that was because she and Bellatrix appeared at this moment to be of similar age. Given that her memory was affected, her brain may also be affected. It could be the same age as her body.