As long as she gets good quality pellets, timothy hay is quite enough. Alfalfa has more protein and calcium than grass hay (timothy is a grass hay, alfalfa is a legume hay), and that’s good when a bunny is growing – but if the bun gets pellets and is thriving, alfalfa isn’t necessary.
It’s good to start young buns on grass hay early – it gets them into good hay-eating habits. It’s not a problem to give a young bun grass hay, it’s rather the other way around, alfalfa should NOT be fed to buns over 5-6 months of age. It’s way too rich and full of calcium. It can be really hard to wean a bun off alfalfa hay, so if you give grass hay and pellets now, you won’t have that problem later.
Grass hay is great for the development of a sturdy and highly diverse GI microbiota. That in turn is key to a bunny’s health. It also helps keep the teeth in good shape.
So, to conclude: alfalfa is good for babies and growing bun, for buns that have been ill and lost weight, for pregnant and lactating does and for some elderly buns that have problems with keeping weight on. To other buns it should only be fed as a treat now and then, if at all.
ETA: Happy New Year to you and Yuna too!