10099/1040x question

For my buddy, who is banned ....

Back story
I did contract work in 2013 and 2014 of which I never showed in regular 1040 return. I recently received a cp2000 form saying I owe taxes from 2014 of which I in turn did a 1040x amended form and got what I owe down next to nothing, sent in the form with a money order. All done. With that being said, here is my question about my 2013...

I never got a letter(irs lady said she had no info on me from 2013) from irs about saying I owe taxes from extra contract work I've done... Shall I amend, pay the taxes or just forget about it? Seems like I should have gotten something just like I did for 2014.