...As a sophomore last year I mentioned an interest in joining the military and they just about died :/ I tried to explain that if I join JROTC this upcoming semester, it doesn't mean I'm obligated to join the military, but it will certainly help with skill building, leadership, and also break me out of this shell I've been in forever.
I mean, I might be petite and weigh like 100lbs wet, but I'm pretty sure I'm not the first one to want to join the military! 
Your size as a sophomore is irrelevant. You are not done growing. I was 19 or 20 when I finished growing; picked up 3/4" between 18 and 20.
I am of the opinion young people should go on some sort of quest and mission to find themselves. Who and what they really are going on into maturity. Something rife with trial and tremendous challenge which they must confront and overcome.
I would agree with that completely.
I have had three or four very trying moments in my life that were rife with trial and a challenge.
1st. Basic Training, age 18
2nd. Officer Candidate School, age 23
3rd. The birth of my oldest child, age 40 (This one was mental/emotionally challenging)
4th. The black belt testing process, age 52
