Similar experience here. The game is very impressive and immersive.
I was halfway in ACT II only to realize that I haven’t even met with Gale (a companion that you can recruit). I went back to do the Gale’s quest recently and discovered what practically counted for me as 10 hours of new content in ACT I.
Now, I think I concluded the story lines of ACT I and can move back to ACT II.
Baldur’s Gate 3, I’ve been playing it since it came out and I’m only on my 2nd playthrough. Looking forward to my 3rd playthrough, hopefully by that time I’ll have the heart to be able to play an evil Dark Urge run.