I'm not sure i can give you much advice in terms of improvement for this piece...it stands solidly on it's own rules....flow, structure and word choice...all present and correct.
The only think missing, or I should not n present...is metaphor and hidden meaning...at least none that I can clearly see...now given the start emotional nature of the work, this may be intentional...but if not...that is all I could think to add...
And if this piece is autobiographical...then all the best to you...I've never cut with knives...but i've harmed myself in other ways....took my years to get rid of the need....and it is worth it.