If I completed my masters could I still apply for green to gold or did I miss out?

Green to Gold is an ROTC program. If you have your masters you really don't need to go to ROTC. If you want to commission you should apply for OCS.

What did you get your masters in? And just like it's already been mentioned, go OCS or look into direct commissions...

Having a Masters implies that you have a Bachelors. Green to Gold is a commission route for those without. In your case, OCS or Direct Commission (depending on what your degrees are in).

Green to Gold is a ROTC program to assist you on your road to a degree. You already have the degree so the only thing to do is apply for OCS.

You tagged AMEDD, are you trying to become a Doctor? If so, I would suggest trying an applications to the Uniformed Services University at this website. https://medschool.usuhs.edu/admissions