I might have resolved my issue:
#1. My IP was, for some strange reason, on a Spamhaus black list. I had it removed (which is ironic because I run a spam bot honey pot on my site lol)
#2. I solved the duplicate domain name issue in mydestination and virtual_mailbox_domain by removing it from the mydestination line in /etc/postfix/main.cf and restarting Postfix.
Thanks falko for the guidance! I'll subscribe once I get the money to do so