My employer has me listed as married, I’m not and didn’t notice until it was already submitted, is there a way to fix this?

Nothing about that has to be fixed.  Your employer may have been withholding tax at the married rate for 2019, but it is what it is now,  Your calculations were done according to the amount shown in box 2 of your W-2.  You can change your W-4 at work going forward to affect how much your employer withholds,