First off, I think you need punctuation. Just refusing to use it harms the poem by making it seem unpolished and it also hurts the flow a lot. Also, be careful about capitalization at the start of each line: Some words are capitalized and some aren't, I'd advise do one of the other and be consistent through the poem.

Onto the content itself. I think it's a good effort in non-rhyme, because it can be hard to break from the habit of rhyming if you are used to doing it that way. I do like the one bit of rhyme at the end: it finishes off the poem nicely and it not obvious, but subtle and unforced. Just a few pointers from a critique point of view:

'a million thoughts bouncing around my head'

^^ This is an example of a line that has probably been said, in some shape or form, in many average poems on here and further afield throughout the years. Why not try something more creative, such as 'an armada of thoughts navigating the oceans of my mind.' That is a little more different but is basically saying the same thing. Even if it doesn't work, if you are trying to grow as a poet its good to experiment and try to make your poems original, because if they are cliche they will not stand ever really stand out for a reader.

I think the poem picks up for the last two stanzas where it is simple but quite touching also and the emotion is portrayed well.

'It doesn't ever come easy for
me to try and be free
They all say it's for the better
but they don't realize the power
that you have over me'

^^
This isn't Shakespeare but it is quite powerful stuff all the same and the readers I'm sure can relate to it. I think with some rearranging of structure and punctuation, it could benefit.

'I sit up at night with
an armada of thoughts navigating
the oceans of my mind -
Pondering the whys, the who's
that have come between us.
I realize that I will never be at peace.

How do I overcome something
I always struggled to understand?
One that I had a light grip on
continues to weaken my grasp.

I try and try to stop these
feelings that have haunted me
with such pleasureful nightmares -

But I welcome the allure of sleep,
so that I can picture clearly
how you smelled of mowed grass,
sang in the shower or the way
you would say my name.

It doesn't ever come easy for
me to try and be free,
they say it's for the better,
but they don't realize the power
you have over me.'

^^
I changed quite a few things on this quick draft/edit. Left out a few 'filler' words, changed some wording and added punctuation. Also, I added some specific detail about the 'smell' part: its usually better to show the reader rather than tell them: e.g. I remember the faint lavender scent that lingered around her' is more descriptive and sensual than simply 'I remember her smell.' I'm not sure if this edit any better or worse but it might give you a fresh perspective on the poem and give you ideas on how to experiment in future. Keep it up! :)

I can really relate to the depth of honest feelings and I feel the finish is strong because the "They'" most often factors in with the whys an who's

I enjoyed reading this piece

I like this poem. :)