In the poem "Hanging Fire," what is the significance of the line "and momma's in the bedroom with her door closed" in terms of "holding back"?

The poem Hanging Fire brings up the worries teenage girls usually have, such as pimples, braces, boys and mostly death. The 14-year-old speaker is constantly wondering about her death, showing that maybe she is so overwhelmed with her teenage problems that she imagines death may be the resolution for them. When she mentions "and momma's in the bedroom with her door closed", it seems her mother is not available or wouldn't understand her fears. So the speaker is "holding back" a conversation with her mother, making her feel alone and insecure.