Nightmare (My first poem)

[addy]

Welcome Maddie . I really like the story you were telling here. As billy mentioned the rhythm isn't perfect (I have trouble in that department myself LOL) and that will take practicing. But you do have the flair of a storyteller. I actually like the repeating parts, they remind me of the song/poetry parts in the Just So stories of Rudyard Kipling

I'll skip the points already commented on

This is no dream, more like a nightmare.
Kicking and Thrashing any reason for the capitalization?, tangles my hair,
The memories flood, wishes fall through,
And the spinning leaves me confused.
A silent scream wakes me to the dark endless night Unless you really want to emphasize the line, I'd advice against piling on more than one adjective to a noun (ex. instead of "dark, mysterious man" just "dark man" or "cipher" can show the picture)
“it’s just a dream.” My whisper hanging in the air
‘No’ I think, more like a nightmare.

Pull my knees to my chest, fill my heart with regrets,
That the dream has re-surfaced again. Maybe "retrieved" is the proper term? (LOL, you can pick a nicer word though). You can have lots of fun with this ("fill my heart with regrets... the dream has salvaged from the deep")
I slowly uncurl, and my feet hit the floor, as I step off my small tower of safety.
One stride at a time, I take the stairs down
When the little girl reminds me of fears
Of spiders and darkness and falls off the tree, Loved this part and most of all being alone.

Step after step, creak before creak,
The tears are flooding a river.
Dripping and dropping, leaving a trail, like memories I shook long ago. I felt an inconsistency when you said the tears are "flooding a river" but also "dripping and dropping a trail". Personally I'd keep the second image, it's far more interesting
I sit on the floor, just one footfall to the gate,
The portal that hides the unknown.

Hold my head in my hands, wipe away tears, and think about those that I love. Try to rewrite this with a phrase or phrases that sound less cliche. It's an emotional turning point in the poem, so you don't want readers skimming over this line. You want it to grab them like all the other lines
A weak laugh escapes as I think of how silly I’ve been.
“It’s just a dream.” I say again, but pray to the Heavens it’s true.
I sit on the floor, the tears slowly pouring, then I realize it’s five minutes till two!
I get up off the ground, and set off with a frown, back to my tower of safety.

Who would have guessed the only my room would be the true doom this line confused me a little, waking me up once again.
The last step in front, but missing the edge, I fall into darkness once more.
I wake with a fright, to a startling sight,
I had never left my small room!
This being a twist of "dream within a dream" (if I'm reading correctly) then this verse should be kept

This is no dream, more like a nightmare.
Kicking and Thrashing, tangles my hair,
The memories flood, wishes fall through,
And the spinning leaves me confused.
A silent scream wakes me to the dark endless night
“it’s just a dream.” My whisper hanging in the air
‘No’ I think, more like a nightmare. Already mentioned liking the bookending of the poem

If you're having trouble with the rhythm, try reading the poem out loud. When you read it out loud and not just in your head, you'll be able to hear the parts where the phrasing or inner rhyme might be awkward, or where you've written a line too long to be comfortably spoken. Basically if it doesn't sound right, it won't read right.

Hope the comments help, and hope to see more poems from you