You can add vege slowly....so one or two types over two week period - if she has any tummy issues or unformed ceacotrophes then stop and its back to hay. Her pellets can be slowly changed to normal pellets I think...someone else might suggest something else here but thats what i would do..again half of one type of pellets and half of the other and a slow change over.
I dont add much veges to my buns diet as one has sensitive tummy...so they do better on foraged foods.
What pellets is she on? You want a complete pellet with a high fibre content...so science selective or oxbow are good ones.
90% or more should be hay in her diet. So a variety of hays is great - usually meadow hay is used as the norm. Timothy is great too. Alfalfa should be now & then.
The pellets are only to give the extra nutritional value that they need being a domestic animals...but should only be an egg cup a day.
They need to be grazing alot...so eating foraged plants or hay is high in fibre and this is whats good for their gut and to help keep thier teeth down..since they never stop growing.
This link will be helpful - Francis - one of the leading experts on rabbits...
https://www.harcourt-brown.co.uk/articles/free-food-for-rabbits
And you can buy this book for £4 - wild foraging for rabbits - really good for getting plants that wild bunnies eat and is by far the best diet for rabbits.
http://shop.rabbitwelfare.co.uk/product/foraging-for-rabbits-by-twigs-way/
She should in the next 3 months or so reach sexual maturity and if her weight is correct its best to then get her spayed...helps prevent cervical cancer which they are prone to. Obviously an exotics vet is best for this procedure.
good luck
Mine are now 5/6 years old...I remember when they were so little..time flies!