The Nonbusiness Energy Property Credit which includes energy efficient windows expired on 12/31/2017. It is possible that it will be reinstated for 2018, as this has happened before with this credit. But as of right now, it's not available.

I added attic insulation to my home in 2017, more than tripling the R-factor. I was told by both the utility company and the contractor that this would be deductible in 2017, but it wasn't. Is it possible this was added later, as you stated regarding replacement windows. If so, should I be amending my 2017 return.

The non-business energy credit was extended by Congress last year after filing for the 2017 tax returns had already started, Yes, if your situation and the insulation meets the requirements, then your 2017 return can be amended.  Here is a link with basic information:

https://turbotax.intuit.com/tax-tips/home-ownership/energy-tax-credit-which-home-improvements-qualif...