
Gluttony |

I picture them as individuals who will vary from each other in height, weight, and other aspects of appearance because they are not clones who can be categorized under a single number for each of their physical features.
At best you might ask what the average height and weight of nymphs/lampads/dryads, which will give you numbers that are somewhat close to the height and weight of most individual members of the race.
That being said, I usually just hover around real-world human height/weight averages for any human-ish race (which includes most medium fey), unless that race is explicitely stated as being tall or short on average.