Only you can answer the question about withholding.
1)If you paid for the exercise out of your pocket and there was no withholding then you should have received the full amount of proceeds, i.e., # of shares sold x per share selling price.
2)If you paid for the exercise via the sale then you'd reduce thes step 1 proceeds by the amount of the exercise cost.
3)If there was withholding then you'd have net proceeds that's considerably reduced from the step 2) amount.
You should be able to call the former employer and talk to the payroll or HR department and get the definitive answer.
