TIL there are people who call themselves Catholic who don't follow the Holy See and think that that's not a contradiction. I guess that's neat.

You're free to believe what you want. Understand, however, that to be a Catholic means agreeing with the Pope/Church on matters of faith. This is not a negotiable part of being a member of the Church. To be baptized and then profess you do not agree with everything marks you as guilty of the sin of heresy, a textbook definition heretic in the eyes of the Church.

I am not saying this to be insulting, this is Catholic doctrine and many schisms have happened over many hundreds of years due to many disagreements on regarding parts of faith and papal infallibility.

There's actually an odd edge case where you could claim to not follow the current or recent popes. I learned this from Luke-jr (the 'prayers in the blockchain' guy), he's a Sedevacantist that believes the last pope was Pius XII and all the popes since were antipopes/pretenders. Since their bishops can consecrate other bishops these believers hold the weird position of being in communion with what most consider the the Church, but do not follow reforms in Vatican II nor acknowledge that a current pope is installed.https://en.wikipedia.org/wiki/Sedevacantism

That's just called Humanism. I think it's weird to say that being baptised makes you Catholic if you don't believe in the specific tenets that differentiate Catholicism from other Christian beliefs.

Like...say for a moment that you were baptised and then confirmed Catholic but then later had some kind of epiphany and decided to convert to Islam. Would you still be Catholic anyway? Can you be an Islamic Catholic?