You don't say what these kids are doing or saying. "Bullying" is a big (and IMO over-used) word. It may be the case or it may be that you have a gentle soul dealing with the rigors of middle school. Honestly I don't know where you get "growing and flourishing as a young lady" MS and early HS are hard on the old self esteem, it's a rocky road out there Dad, buckle up.
My 13 year old (eighth grade) gets in the car nearly everyday after school talking about how her friends and classmates act like jerks. She tells me things they say that many would call bullying. We discuss strategies for dealing with it, her sister talks to her about her similar experiences in middle school. My kid is pretty emotionally tough so she deals with this stuff differently than some kids might, but all in all she's pretty miserable right now. Feels like her "friends" are two faced, her classmates are mean and there is a general immaturity and cruelness to her day. Sadly, that has been our experience of middle school, myself and husband have similar memories.
We talk about what she may be contributing to the situation and what to do when it gets really bad. She can speak up... "Mom it doesn't matter what I say these kids will never stop". She can walk away..."but then I'll be all alone at lunch". She can put up with it and go along to get along "they are just so bitchy and mean". As you can see, no easy answers.
I guess my advice before you go into protect mode would be to define bullying, help her see that all kids struggle during this time and whatever you do don't feed it.
If she is truly being singled out and bullied with a group of the same kids ganging up on her day after day then you need to speak with the school. She must be clear and specific about what they are doing and saying. Be very careful opening up that kettle of fish!