I just set up mail myself last week. Postfix on FreeBSD over at DigitalOcean. Did everything you did and was quite frustrated that my wife seemed not to be gett

I just set up mail myself last week. Postfix on FreeBSD over at DigitalOcean. Did everything you did and was quite frustrated that my wife seemed not to be getting my email. The thing is, I sent a test email before adding SPF, and then one before adding DKIM, and Gmail figured out they were all part of the same "conversation" so because the first one seemed spammy the rest were penalized. I made my own fresh Gmail account and messages go through fine. So I'd try that: make a fresh account from the one you've been testing with, and see if mail goes through.