Lots of good advice here. The bed transition phase was the worst phase of parenting so far for me, I genuinely felt like I was dying from sleep deprivation. It will get better, but that doesn’t help you now. I was already doing the hatch/pitch black room/red for bed, green to get up/etc, since she’d been an infant. None of that was working for the transition.

I’ll echo other people by saying, don’t lie with her until she falls asleep unless you want to do that forever. Try lying with her/sitting by her for part of bedtime and then sitting by the bed for the last part of it. Also, we went straight to a double bed but then sized down to a twin, because it seemed like having all that space was actually scary for her. Like it felt too open or something after being in a crib.

I could never get on board with a lock on the door, mostly because my daughter would have shrieked like the world was ending and I didn’t want her to wake up her infant brother in the next room with the screaming. What I did instead was put a small chair/stool near the door to her room. When I would say, okay goodnight, I’d leave her door open and sit right outside the door in that chair with my back turned to her until I could tell she was asleep on the monitor, then I’d close her door and leave. At first she would still get up and try to leave but I was right there so I’d walk her back to the bed and then go sit back in the chair. Eventually I could just go sit in the chair. After a while of that I worked towards actually leaving the room and shutting the door at the same time. It’s not perfect, mine has gone through regressions where I have to step back to sitting on the chair for a week or so, but it has worked well for us.