I don’t know the circumstances surrounding how she came to you, but considering her age, it is unlikely she is already spayed. Unless she came from a shelter, of course. They tend to spay rabbits young so they can get them adopted ASAP.
Going with the assumption that she simply doesn’t have a uterus, this isn’t completely unheard of. Rarely, rabbits can be “underdeveloped”. Or… they can be intersex, which happens more often than people think.
I’m curious about the peeing. Does she seem like she is able to hold it? Or does it seem more intentional? Sometimes a spay surgery can injure the muscles/nerves down there which can lead to incontinence. Assuming this is more “intentional”, perhaps there is still something there that the vet missed? The presence of ovary (or testicular) tissue = hormones = hormonal behavior (e.g. territorial marking).
Fun fact: Despite what many websites say online, male rabbits actually do have nipples. They are just very, very small and flat and difficult to identify under all that fur.