The IRS has not been processing any mailed documents for some time so that may be the reason you have not heard anything.
If you want to mail it again, the form says to mail it to the same IRS center that you would mail your original tax return. Here is a link to find the center for where you live: https://www.irs.gov/uac/where-to-file-paper-tax-returns-with-or-without-a-payment?_ga=1.31357439.177...
