SS Route Via Ireland Point of Entry

[surfrat]

I apologize if I've posted this in the wrong place...

My spouse is a British citizen, while I'm an American.
We came to the republic of Ireland to pursue the Surinder Singh route prior to Brexit, but while talking with a new acquaintance today, we've grown concerned we went about it the wrong way. We came on the ferry from Cairnryan to Larne, Northern Ireland, then drove into the republic, where we're living. We didn't encounter any border control, and the only "stamp" in my passport is from our airport entry into the UK which is a visitor pass and only permits me to stay in the UK for up to 6 months, and doesn't allow me to open a bank account.
We were told today that we should have taken a ferry directly to the republic from the UK, so that we would have gotten our passport stamped and explained our intention to pursue my spouse's freedom of movement.
Is this true? We still have 4 months....should we leave and go back in again this way to establish my entry?
Thanks for any help anyone can offer.

[CR001]

What date did you arrive in Republic of Ireland?

Have you done any of the formalities required in Ireland as a non EU citizen?