Bayli has been sleeping with me since she was about 4 months old (2.3 lbs). The first week she slept with me I woke up many times throughout the night to make sure she was okay and I hadn't rolled over on her. Luckily, one side of my bed is against the wall so she sleeps on that side. Now she's two months older and about 1.5 lbs heavier and takes up the majority of the bed.
But it's easy for me because has stairs to go and up and down when she pleases. I would say just try to keep your pup from the waist up so in case your feet move around they won't get thrown off.