Anybody know where I can find a youth Aggie soccer jersey for my daughter? I can't find them any where.

They don't make them

If you are in College Station, you could try the camp store during the summer soccer camps. The last week of June is the day camp for the younger kids and the camp store is in the players lounge at Ellis.
I bought a jersey for myself last summer. The kids get jerseys during the camp, but I think I saw kids sizes in the store.