I think that bringing up a kid is the most important, blessed and tiring stuff in life.
..but what does scare me is, if I'm gone, who will protect her?
This was the scare of my neighbour as well. He passed away and his daughter is able to protect herself, and your daughter will, too. All you should do is to leave her in much better conditions, especially economic.
I just worry about passing before she is capable. I think she will be able to take care of herself later - but at five, no. My wife is strong, but different.