Sorry, just seeing this! Please switch her off of the Fiesta and on to a pellet-only food. It's very unhealthy for her. Look for something with 16% or less protein and 18% or more fiber and absolutely no treats mixed in. If you're going to a Petsmart, some sell Oxbow and like Tonyshuman said, their alfalfa pellet (15/23) is really good. If I remember right they usually carry Mazuri which is pretty good quality too. I don't like any of Kaytee's alfalfa pellets.
If you can get to feed or farm stores you can usually find great quality foods that are often better than the pet store stuff andmuch cheaper. You just have to buy in bulk, like 40 lbs for $15. If it's too much, donate the excess to a shelter and you'll still save money. I feed Heinhold's 15/20 show formula for my baby bun and I really like it. Other good brandsinclude Pen Pals, Blue Seal, Manna Pro, and Purina (although some people have had quality problems with this brand).
Timothy and other grass hays (bermuda, bluegrass, etc.) are the best. You can feed any of them although timothy is the easiest to find in pet stores. I buy bales from local farmers, usually they're timothy/bluegrass mixes. You can feed some alfalfa since the bun is a baby although I usually just use that as a treat.
As for treats, I say don't feed any till you get the bun weaned off of the Fiesta. All that sugary stuff makes it very easy to cause tummy upsets and diarrhea in baby rabbits. I usually give small treats like dried cranberries, bits of fresh apple or grape,dried rose hips,or rolled oats but I don't give them often.
Also, check out our Feeding FAQ:
http://www.rabbitsonline.net/view_topic.php?id=16340&forum_id=48
And the Library thread on feeding:
http://www.rabbitsonline.net/view_topic.php?id=12046&forum_id=17
