I have to admit that I was loving the inconsistent and unpredictable nature of the flow towards the beginning of the poem, but then it seems you delved into a more comfortable mode of familiar stock phrases (the second-to-last stanza consists almost entirely of what I'm tempted to call cliche, for want of a less loaded term) and musical sound effects.
The last stanza turbo-charges the flow of the poem with heaps of internal rhyme and a falling rhythm with heavy stress on opening words. It tends to make the poem's conclusion sound light and sing-songy, and I think it might be more effective if you broke it into shorter lines to add a kind of caesura where one's scansion might get the better of him.
As far as the semantic side of the poem is concerned, I greatly admire your control of the vagueness that's so key to this poem's tone---the prevailing tone of confidence overcoming the vagueness of what could be, the intention to "take the plunge," to disclose the "something" that got away, is quite courageous. You do well to resist any difficult metaphor or comparison here, as that would certainly have implied too much control...
If you ever want to take the time to revise this, I would suggest a much slower meter towards the end---less music would allow more intimacy, and make the poem seem more personal, in my humble opinion.
Thanks for letting us in on this one, Alicat...
"God becomes as we are that we may be as he is." ~William Blake