Hi Rach,
I have done USAG but they don't have adult meets that I know of; they just have the age group 16+, which is almost 100% high school. There is AAU nationals in June in Savannah Georgia (try googling that) and I am doing USAIGC and they have been very helpful in registering me as an independent, because my club is not a member. They have age groups 19+ and their website is
USAIGC. Their meet and registration fees are very reasonable as well. Good luck!