I am exactly in the same situation.
Missed one week trip to US, and i asked the officer if this will be an issue, and she said no since I have about 300 days buffer.
It has been 3 weeks since the test and no update.
https://g.co/kgs/b1Ri1m
She asked for 7$/stamp, but I told her I am paying only 4$.
You should be within this range, depending on the number of stamps you have.
I did not pay any additional fees.