How do I correct this behavior?

My pup is a German Shepherd Golden Retriever mix. She's 11 years old, and will be turning 12 in September, so age is a factor. She has had a recent vet visit and is perfectly healthy and impressed the vet for her age. My husband and I decided a few months ago that she could no longer sleep in the same room with us. There are a few reasons behind this decision, such as sleep disturbances (she wakes and pesters when we stir in the night) and a baby on the way. We don't want her to knock over the bassinet or disturb the baby or us any more than we will already be. She is allowed in the room when we are awake, but when it's time to go to bed we escort her out of the room. At first, she tolerated this, then she would grump and not move at first. After about a month she started outright refusing to leave the room at all when she knows what's up. Now she growls and snaps and makes a big fuss, almost to the biting stage. Needless to say, I am concerned. She has a bed that she never uses, that we use to store her toys. She has not accepted the bed and her things being moved to the room next to us to show her a new "space" for her to be at night. She sleeps in the hallway outside the door and shows pretty extreme (for her: normally a VERY docile doggy) "resting place aggression." Our best nights are when we've spent the evening in other places in the house and go to bed late and don't invite her in at all, but it can't be that way every day! There will be times when "family time" is in the bedroom, and bedtime, she's not allowed to stay for. We've tried cajoling her, begging her, tricking her, enticing her, but there's nothing she wants more than to stay in the bedroom. I've tried giving her some time to get used to this arrangement, since she has had that sleeping space for 4 years now. I decided to move her soon after we found out about the pregnancy because I didn't want her to associate the baby with her being kicked out. Time is getting short though and I'm running out of ideas. Help!