Troubles with toddler sleep

My daughter turns 2.5 in December. She has been a great sleeper for a long time (since she was about 3 months). But since we took the front bar off her crib and turned it into a toddler bed, most nights she wakes up at least once, sometimes as much as 3x. Sometimes it’s because her favorite stuffed animal falls off her bed, but most times I have no idea why she wakes up crying. She almost always goes right back to sleep when I tell her to lay back down, so I’m not up for that long. But still, I really miss sleeping through the night. If I don’t come into her room, she heads for the door and tries to find me. I know this is a pretty mild sleep problem compared to some, but I would like to get her back to sleeping through the night. Any advice?