like an iceberg between the shoulder blades (line 8)
This imagining of death is almost the sensation of fear, that shiver down our spine. Ever heard the expression of an 'icy feeling of dread'?
I want to step through the door full of curiosity" (line 9)
This is the pivot, the turning away from fear. Our speaker is announcing that despite all that we might normally be terrified about, she will not be afraid. She chooses instead to be curious, to be open to amazement that is available if you step out from under the fear.
I don't want to find myself sighing and frightened (line 26)
Now our speaker makes it even more clear that it is her intention to take a path that leads away from fear. There's the sense that, as well as not being much help, the fear would be a waste, getting in the way of the possibilities and wonder that might exist beyond this life.