I think the cage you have is too small.
(48cm x 29 cm is about 1ft x 1.5 ft for those who don't know, and the rabbit is probably about the size of a dutch)
The minimum size for a cage is one that has space enough for food,litterbox and an area big enough for the rabbit to completely stretchout and tall enough that it is able to sit up comfortably. Like aglunusaid, this is usually about 4 times the size of the rabbit.
Whats even better though, is a cage big enough that allows the rabbitto hop around some and play, especially if the bunny spends severalhours per day in the cage. The bigger it is, the better. A decent sizecage from a pet store will usually be very expensive, but there aremany options for making your own cage that are much more affordable,and there are plenty of people here who would be willing to give youtips.