Is she only 7.5 weeks old? Or is that how long you’ve had her?
If she is only that old, she is still a very young baby, and should really still be with her mom.
If she’s a baby still, it will be hard to potty train her until she gets older, just like human babies. If she’s older (a few months old), then she is prob hitting puberty, which also makes things hard, and you should start thinking about getting her spayed (usually this is done at 6-8 months of age for females, but depends on the vet).
It helps to continue doing as you have been, make sure that there is only bedding in her litter box (not everywhere in the cage), and that there are not soft things or grass mats in the cage. Make sure she can only access her hay from inside the litter box, as rabbits tend to poop while they eat hay.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.