I am a 24 year-old graduate student. Last year I was a full time student from May-Dec but worked Jan-April and supported myself. How do I file?

I am a current full-time graduate student that turned 24 at the end of last year. I worked full-time and supported myself for the first 4 months of 2018 (made ~$8k). I started grad school in May and have been a full-time student since then. My parents do not support me with the exception of me still being under their health insurance. I filed my taxes independently already and my return appears as "still being processed". I received a request for a 1095A and an 8962. However I have been told by my parents they were planning on claiming me as dependent. What are my next steps? Do I submit the documents above and then amend my return as a dependent? Is there another way to handle this situation?