Is it normal for an 11 year old girl's genitals to be swollen/enlarged? she has not started her period but is developing.

This : This is not normal, however you need to realize that what seems swollen or enlarged to you may in fact be normal. It is difficult to say without seeing the area myself. She may be dealing with an infectious process or even an allergy. She needs to be seen by her family doctor or her pediatrician. All the best.

Hard to say: Your description is vague and may or may not be accurate enough to say what is happening. The inner lips of a girl may grow quite a bit during puberty, from a minimum or "innie" appearance to major "outie" look. One side can be larger than the other. If the tissue is actually swollen, and not just different, it deserves an evaluation by the doc.