Thank you for adopting this rabbit!
It normally takes some time to bond with a rabbit. Rabbits are not like puppy dogs, rabbits are flight animals whose instincts tell them to be seriously cautious, or else they may become someone’s dinner. What you describe sounds perfectly normal, especially since she was spayed quite recently. (A spay throws the rabbit into hormonal turmoil, which needs some time to resolve. Hormonally driven territorial behaviours such as marking and aggression often become more marked for 2-4 weeks post spay).
She marks your bed because a) she’s in a new place that needs to be claimed and b) it has a strong scent of you. To a rabbit, that means “this is the place to be, the best spot!”
Marking is not a dominance thing between a rabbit and a human. Dominance in animals manifests between members of the same species. Your bun knows you’re not a rabbit. Pushing her head against the floor is pointless, even counter productive. It is always the dominant bun that puts its head down in demand of pets from the submissive bun. Your instincts are sound!
It’s very promising that she’s not being food aggressive with you.
I think you mostly need to be patient. It can take months for her to trust you fully, but that’s how rabbits are. They are food for so many animals, they cant afford to go around and just trust anybody.
We’d be very happy for updates on how you get on. To gain the trust of a rabbit is a wonderful thing!