All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
By the grace of Allah, you are not a devil and you are not cursed by Allah, Allah willing.
Sleeping on the right-hand side is a Sunnah and not an obligation. Therefore, you are not at all sinful for not sleeping on the right-hand side. However, if you can accustom yourself to do it, then it is better, but you are not blamed for not sleeping on the right-hand side.
Allah knows best.