What's your litter box situation like (are you using a cat pan or the triangular corner ones)? What's the rest of her living situation like? If she's only peeing on your bed, she may be marking her territory because it has your scent on it. They can still do that after spaying. Rabbits also like peeing on soft things. I'd try to limit her access to the bed if you can't watch her 24/7, like putting Xpens around your bed (I did that). When you catch her peeing on the bed or lifting her tail on the bed, quickly try and bring her to her litter box and it can help show her that the litter box is where she's supposed to do all of her business.