The speaker of the poem is Elizabeth, who may or may not be Elizabeth Bishop herself, who may or may not be recounting a real childhood experience. As we discussed in our "Summary," some of the "facts" of the poem are not actually true. The February 1918 edition of National Geographic does include photos of volcanoes, but it doesn't actually include any of the other things that Elizabeth mentions. There are no naked women, no babies, and no dead men on poles.
This makes us question whether we can read the poem as autobiography. Actually, this makes us pretty sure that we can't read the poem as such. It's a fictionalized and poeticized version of an actual life event. (Or is it? Did Bishop make the whole thing up and name her speaker Elizabeth just to toy with us? You never know how poets get their kicks.)
The other important thing to realize about the speaker is that she's telling the story in the past tense. In this way, there are two Elizabeths in the poem. There's the young Elizabeth in the waiting room, and then there's the older Elizabeth who recounts her experience in the waiting room. We don't really know how much time has passed between the telling of the poem and the actual event. Has it been a year? Ten years? Fifty years? There's no way to know for sure.