I can't remember off the top of my head, and my lecture notes are aaaaaaaaaall the way upstairs ( :wink: ) but I think rabbits should get about 16% protein in their diets. This lessens with age, and increases with pregnancy/lactation, etc, but it's the average. Check that your feeds have enough protein!
Fibre isn't as important in a staple feed as hay should be the main source of it.
I feed my two mini lops 60g of Dwarf/Junior Supa Excel a day. That's about half of what they should be getting, according to the bag, but if I feed more, they get soft pellets...it's not that expensive, really, as I feed much less of these pellets than the muesli mix they were on when I got them...