Thanks for the additional information. It is helpful.
It is possible that her previous owner abused her so she is a little hesitant about staying close to you. However, once you are going to bed, she might feel safe enough to stay with you. Many females are submissive to male humans. Dogs associate low tones with reprimands and males tend to lean over dogs and have low toned voices while females have higher pitched voices and crouch down to interact with dogs. That leaning over to a dog indicated dominance.
It might be helpful if you try and raise the tone of your voice and crouch down when interacting with you. In addition, I would start obedience training now. It doesn't have to be a class. You can do it at home. It will help teach her what you expect of her when you say certain commands and will lead to her being more comfortable around you and now what you want her to do so she doesn't have to be scared or hesitant around you.
The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
We also don't recommend dogs sleep with owners as it raises them to the same level as humans and sometimes will cause a dog to not obey their human master. However, if she seems to do well with training, just keep it in mind as something you may want to try later.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer.