I'm extremely stuck on the heart room. Every single timing is just slightly too close, and it feels like it was designed to be impossible, but look possible.
Oh, trust me, I think I made the same mistake as you did.
Hint: Do NOT go up the passageway with the tight window of timing - that droplet is there to discourage you from doing this exact thing.
Bigger hint: Remember that random small meat block next to the guard? You need to get rid of it to progress.
Another hint: the droplet on top of that block's placement is intentional.
biggest hint: get punched across the room by that guard, and you'll be on the path to progress!