Quote: Ok...but your daughter, as your describing, doesn't sound like the average senior. 18 yr olds vs 14 yr olds there should be no contest in terms of physicality. Bigger, stronger, faster on average beats smaller, weaker, slower.
I believe most girls complete their growth spurt by age 14-15 (9th grade). My point was that the difference in size is not necessarily determined by age or grade. I coached a U18 girls team this past fall and there was a large variance in size of players on my team as well as the teams we played against. I'd estimate that the heights of the eight seniors on our high school team range from 5'2" to 5'9". Both our tallest and shortest players are juniors.