"Myself is a synonym for everyone else these days,"
I don't really like the "these days" at the end of this line.

"And I keep finding myself standing in front of the mirror,"
No and needed.

"Then wondering how I ever got where I am when"
Wondering how I got where I am,
Everything upside down and inside out.

"I can't remember the last time I saw myself smile"
Yeeeeeeeeeeeeeeeeeeeeeaaaaaaaaaah.
A little too literal? I like how it isn't in the self loathing sense, although idk. The idea has been used so much in the BAD sense that when someone actually puts it into a poem WELL it sounds cliche :(

"In a way that my pupils don't dilate and my brow creases,"
I like how you've expanded the idea of the line previous however I think this line could be cut down a little.

The rest doesn't do much for me. I don't know. I know this isn't your best, you'll get there eventually.
And I love you x