Emily Dickinson - a poem of despair

I noticed that Emily Dickinson wrote about death and despair a lot.  It makes me wonder about her life, the kind of pains and toils that were levied on her soul.  Her poetry is also usually cryptic, but one poem, 510, that is about despair is a piece of her literature that I think I understand fairly well.  The first half goes:

It was not Death, for I stood up,

And all the Dead, lie down—

It was not Night, for all the Bells

Put out their Tongues, for Noon.

It was not Frost, for on my Flesh

I felt Sirocos—crawl—

Nor Fire—for just my Marble feet

Could keep a Chancel, cool—

And yet, it tasted, like them all,

The Figures I have seen

Set orderly, for Burial,

Reminded me, of mine—

I found it interesting how Dickinson explains her experience with despair by comparing them to things that it is not: it’s not death, but the senses are just as numb; it’s not night, but it is a kind of darkness; it’s not frost, but feels just as cold in the spirit; it’s neither fire, but similarly wild and destructive.  Then the death in her life, the burials of others, seems to remind her of her own emotional burial.

                Then Dickinson writes:  

As if my life were shaven,

And fitted to a frame,

And could not breathe without a key,

And 'twas like Midnight, some—

When everything that ticked—has stopped—

And Space stares all around—

Or Grisly frosts—first Autumn morns,

Repeal the Beating Ground—

But, most, like Chaos—Stopless—cool—

Without a Chance, or Spar—

Or even a Report of Land—

To justify—Despair.

I’m assuming she means she feels trapped, stifled, and separated from the world ("fitted to a frame"), and the “key” to her escape from this agony is missing.  Although one thing I can’t decide is whether the thing that ceased to "tick” is the speaker’s heart or some other mechanism in her spirit or mind.  But then she writes about “space” (a cold, dark, empty void) that surrounds her, and a “grisly frost” that freezes over and stops what I’m assuming to be her heart (“beating ground”).  Whether it kills the speaker’s body or spirit I’m unsure, but Dickinson explains that despair – like “chaos” – is undefeatable.  I’m wondering if “report of land” means that the speaker is stuck out in a metaphorical sea, alone, with no sign of land or hope for the end of the treacherous waves of despair.