OK, don't give treats from the petstore. Those are generally horrible for your rabbit's guts (digestive problems are likely to kill your rabbit, it's not something you can take lightly). Rabbits should eat hay. lots of it. About her body size in hay everyday. If she doesn't, she'll get teeth problems and guts problems which are very serious and could lead to her death a lot quicker than you think. The second thing she'll eat as an adult is vegetables. Fresh from the market vegetables. About 8% of her body weight with 2/3 leafy greens and 1/3 other vegetables everyday. You can begin to introduce them now. One by one, slowly over the course of several days for each vegetable.
Pellets are a complement. Your rabbit can still eat quite a bit of it (as long as she eats her hay!) while she's still growing but after that it's around 2-3% of her body weight each day (my Nethie eats about 10g of them). I don't know Living world pellets, but I just looked up the composition and it looks pretty awful. There isn't anything in there that a rabbit should be eating (salt, corn, soybean aren't meant for rabbits, who are strictly herbivors). You'll have to transition to something else - you can look it up on the forum, several brands are recommanded, I wouldn't advise you on this because the one I use can only be found in Europe... I seem to remember Sherwood is pretty good.
My personnal rule is no treats because I feel it does more bad than good, but you can give a small piece of fresh fruit or carrot once in a while if you feel like your bunny need some.
To know everything about nutrition, I recommend you and your son go read the articles about food (the vegetable list is especially useful) here:
http://rabbit.org/category/care/diet/
It has nothing to do with nutrition, but considering you sound like you are a beginner rabbit owner, I feel I should tell you : since you got a doe, you know that you'll have to get her spayed, right? She's got over 80% risk of getting uterine / ovarian cancer if you don't, some does get this around their 2 or 3 years.