Hello, I received a 1095-c after I filed. should I amend my return or leave it alone? it's for employer-provided insurance and it's around 120$.

good news a 1095-c doesn't get entered into your return. keep for your records. 

No, you should not amend your tax return. 

The only 1095 that must be reported is the 1095-A.  Both the 1095-B and 1095-C do not have to be included on your tax return.