You said that you have cut out scary movies and such before bed -- but you may want to forgo them altogether for a while, until you get this issue under control. I went through a period when I was a teen where I was reading Stephen King a lot because he is such a good writer, and I finally had to quit reading him completely. (And yes, that got rid of the nightmares I was having at the time.)
I am curious as to the origin of this problem. It doesn't *always* help to know the origin of a problem, but frequently it does, so if you can kind of relax and let your mind drift and see where it takes you, perhaps you can remember the origin of all this, or have an insight into it. I remember when I was very little, my older brother used to force me to watch scary movies with him. So of course I had these images in my brain which caused me problems ... anyway, do you remember anything of that sort? Were these ideas somehow imposed on you from outside, do you think?
Another thing which might help you, if you are the religious type, is prayer. I don't often advocate prayer as an answer to an anxiety problem -- but it sounds like you feel like there is a "supernatural" component to this -- the old boogeyman under the bed thing. If you do feel that, and you have belief in a higher being, then prayer to that higher being to protect you might relieve your anxiety enough to get some good rest at night.
If this all doesn't clear up in a reasonable time period, you might want to talk to your doctor about it. It sounds like you are young, since you are still living at home, and that this severe anxiety has started relatively recently. Medication can really nip a lot of anxiety in the bud! But it seems to me (from my layperson's point of view) that the longer you let severe anxiety go on, the more entrenched it tends to get. If this anxiety is new for you, then perhaps it would be a good idea to get some professional help before it can really get going with you. I sure wish I had started meds right when I first started having anxiety ... sigh ... anyway, something to think about for you, perhaps.
Good luck! Let us know how it goes.