It can take a while... Remember, you probably aren't the only person applying. I know a lot of rescues won't contact you if they see a problem in your application. I know there were two people who applied for my first foster who were not contacted because one was really old and the other had a pool without a fence around it.
Good luck in your search! I know it's not always the easiest process, but rescuing really is the most rewarding way to get a dog