Is a Demon/ghost following me or am i just 'hallucinating'?

A couple of Days ago, my parents were out and it was about 3:00 am. I was sitting in my room, which is at the end of the hall, and at the other end, is the door to the attic. It was open, next thing i know, i watch as it slams shut right in front of my eyes. I believe in ghosts/demons, so i said, in actually a mean voice, If your there come and get me. Ever sense then, i have been seeing shadows , and when im alone, i would hear people saying my name. Then, last night, i went upstairs be cause i heard this eerie, blood curdling moaning/hissing cause i thought it was my cat, turns out, my cat was outside. And i had said, I know your up there. I walked away and whispered (close as i can remember) something like Come and get me or Come and find me. Right now, its 11:47 pm, and i feel like someone is watching me from the corner and i feel like someone is standing right next to me, wanting to whisper in my ear. and even my cat is acting strange! She keeps looking in the EXACT corner and around that area and hissing. Im really freaked out, and i need some help.