Even if you can feel her backbone, I would actually cut back on the pellets to 1/4 cup a day. At this age she will start to put on weight and grow to her full size (which may never be any larger, btw) so you want her to maintain with the unlimited hay & greens as her main food source, supplemented by the pellets daily. It sounds like you have a healthy bunny and are doing things very well for her.
Have you had a vet do a basic health exam yet? If not, it’s a good idea to get a baseline exam when she’s young and healthy so you can be sure you have a vet you know and like, have a record there of what is normal, and then know who to call if you have a problem. A good vet will check her teeth, her body and may do some blood tests just to have it on record, and can reassure you about what is and is not normal for your particular bunny. You’ll get to know her behavior and shape by feel over time as well. (LOL I mean the bunny, not the vet!)