OP here. Thank you ^^ I was a bit afraid of "you aren't supposed to play Dark Souls this way" comments. Phew.
Anyway, we are now on Lothric Princes. Overall the game doesn't feel much harder. Except for one thing: I am not very good against shielded knight opponents and there are much more of them from Anor Londo and forward. They were okay 1vs1, but they come in groups now. Oh! And one more exception: The Irithyll Dungeon. The game suddenly decided to become a horror. Those Jailers are the worst thing I've seen in this game. Not so much hard as unfair and dumb. It doesn't matter how good you are, they will still manage to take your health down. UGH
Otherwise the game feels as challenging as it was in the beginning - not more, not less - and it is great: the difficulty rises smoothly to match grown skill.
When it comes to bosses, they still aren't much of a challenge. We've had a hard time with Pontiff trying to parry him or roll, but once my bf tried to just block his attacks with a shield, he won first try. It felt very stupid and hardly rewarding. I don't know, I was disappointed. He went ahead to take down Aldrich 1st try, Yhorm 1st try (with help from Siegward) and Dancer 3rd try. I started feeling inferior until we got to Dragonslayer Armour and I got lucky to take it down on my 3rd try. Who knew I could do it after struggling with knights the whole game? Confidence restored! I wonder how Nameless King and Cinder will go, but as of now I wouldn't call Dark Souls hard, it is fair and you can't afford to relax, but it is not hard.