The poem is fourteen lines, but not a sonnet, but acts like one. There's no definite rhyme scheme or iambic pentameter, but there seems to be a volta in the poem like an Italian sonnet. But then again, this poem plays out as a narrative -- a slightly humorous, retrospective narrative.
Why state this is humorous? I've reread this poem many times trying to grasp it, but I didn't give it time to sink in. The aspect of this poem that caught my eye was how overblown the simile is:
So long I have been carrying myself
Carefully, carefully, like a small child
With too much water in a real glass
Clasped in two hands, across a space as vastAs living rooms,
The poem first introduces the speaker self carrying this sort of burden. What, we don't know, and this adds to the humorous aspect. Then the simile comes in of "a small child / With too much water in a real glass / Clasped in two hands." First, the internal rhyme scheme of "glass" and "clasped" and the special attention that the child is holding a "real" glass brings an overly detailed aspect -- perhaps referring to a paranoia which becomes overblown in the next couple of lines
[...] across a space as vast
as living rooms, while gazes watch the waves
That start to rile the little inland sea
And slap against its cliffs' and transparency.
Note that the rhymes come fast and punctuated, "glass" and "vast," and "sea" and "transparency." It seems like the speaker is trying to keep it together the most simplistic way possible. Also note it's just a "real" glass filled with water being referred to here -- not so much a big storm. But this is the point, I think, in the poem -- is that the speaker is aware of this as humorous and the actual core of the poem is in the eighth and ninth line "Revise and meet, double their amplitude, / Harmonizing doubt from many ifs."
The symbols are revealed -- doubt and the revision of doubt adding up. I don't know if this refers to the actions or the end result of "carrying myself." in any case, the speaker adds tension with the lines. "Distant frowns like clouds begin to brood. / Soon there is overbrimming. Soon the child." With these lines, the speaker is deflating his own imagery -- as though to let go of the anxiety as the simile of the child's narrative ends with:
[...] Soon the child
Looks up to find a face to match the scolding,
And just as he does, the vessel he was holding
Is almost set down safely on the bookshelf.
To me, there's a lot going on with these lines that are heartbreaking. First, to reassure the speaker, the metaphorical child finds something -- which is actually a someone -- that scolds him as much as the speaker seems to scold the self. The second is the last line with the key word being "almost" -- by "almost" setting down the glass safely on the bookshelf, it seems that the doubt or paranoia is assuaged for now. Until it rises up like the waves that start to rile the little inland sea.