Did you mail it certified mail or another tracking service so that you have proof that it was delivered.
What does the IRS web site say?
You can check the status of your mailed amended return at this link.
https://www.irs.gov/filing/wheres-my-amended-return
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**