Claimed as a dependent wrongly by someone else in 2015, can I file an amendment for that year now stating I was not actually a dependent?

Tricky situation. I had only lived with my former parents that year for less than 5 months of 2015 (January-beginning of May), and they did not provide any form of support to me after that time. I somewhat re-call that upon e-filing for that year as someone who cannot be claimed as a dependent, my return was rejected as the had indeed claimed me. Despite supporting myself for most of 2015, I eventually filed as a dependent as I did not want to communicate nor hassle with them, though this drastically reduced my refund as a full-time student. Can I now in 2018 file an amendment stating I was not actually a dependent in 2015 to get back the refund money I had lost that year as my financial situation now is getting a bit dire? Any insight would be much appreciated, thank you!