File wrong Tax in 2018- Can I file amend tax return for 2018 ?

Hi, 

I am an international student, I became a Resident Alien on 1/1/2018, but I didn't know it until this year when I finally got an on-campus job.
When I file a 2018 tax, I made a mistake by filing an 8843 form instead of a normal tax return.
I want to address that besides the scholarship I got from school, I didn't make any income.
I want to ask if I should file a late 2018 tax return? Or can I amend my 2018 tax return?
Please advise.

 

Thank you so much for your help, 

Best!