Hi there
It sounds like your LO goes to sleep so well - when Zander started 45 minute napping I was also having to spend the first 20 minutes of his sleep with him to stop him waking up and that was once I got him to sleep in the first place, it was really tough. You should be proud
I personally wouldn't change your wind-down if she only needs a short one and goes to sleep fine.
If she's feeding well after 3 hours then you might want to stick with it for a while longer, though perhaps don't worry so much if she's still sleeping after 3 hours and you want to stretch the odd feed to 3.5 hours.
A really effective thing to do with blackout material is to velcro it to the window frame and that way absolutely no light gets into the room (from the window anyway - it always came through from around our door frame!).
Good luck and have a good weekend
Kelly x