I sent in my amended return awhile ago for 2017 and it isn't showing up on their tool or phone number. I am getting close to the 2-year deadline... any ideas?

An amended return has to be checked here https://www.irs.gov/filing/wheres-my-amended-return , 

not at the regular Where's my refund site.  And it can take up to 3 weeks for it to show up there.

Here is information on how you can reach the IRS by phone for further assistance:

https://ttlc.intuit.com/replies/3301592