I haven't been to a therapist since I'm 11, I can't really tell if this is anxiety, does anyone else here relate to this?

I get this thing, that I get really scares out of nowhere. I think it just went away. It happened about half an hour ago. I was doing normal and suddenly my perception of the ambient changed and I felt observed, I was in the toilet and there's a window that faces outside, about a meter of yard space before a wall it's night and it's all dark, I was almost frozen there for almost 20 minutes unable to turn around to the window.

Thankfully I was on my laptop this time and could get a couple friends to talk to me and that allowed me to move and get to my room. Other times I haven't been lucky, like a couple years ago when I was 12 it happened and I was in bed in the middle of the night sleeping in the guest room with an uncovered window (ever since I have courtains I accomodate them carefully so they completely cover the windows) and bunch of boxes in front of the closet and in the dark I imaginated there were creatures wandering around and looking at me and I cried a lot and felt so overwhelmingly scared and couldnt't even get up to get my mom from her nearby room.

It's not like a childish there's a monster in my room, I've always been completely aware there is nothing but I just cannot help the overwhelming feeling. Since I'm a small child I've ran countless times into any room I'm going to looking behind my back and hurried to close every doors and have my bed in a corner so I can hide my face and not see anything that is around me. It's like if there was someone in every wall and under every bed and standing in front of every door and window and I know there is no one anywhere but I feel watched and followed.

It's the most intense at night, at day is very mild. Doesn't happen always very often, it's mostly picturing someone running after me everytime I'm out of the sight of other people and I can escape it by running to where others are.

I like consuming horror media (like films, art, stories), alternate reality games, mildly bizarre content but none of that ever actually scares me. That is not the cause, this has been going on since I'm a toddler. The horror media could at most have made the ideas more creative, but it's not what I imagine there, is that I physically cannot control how I feel about it, I rationally see there's nothing but every part of my not rational self screams that something is after me.