Thanks everyone I think I'm more reassured now. I guess it's just an irrational fear that I get sometimes because I'm in a lot of pain (physically and because of that, emotionally too) I can't help worrying that even death wouldn't end it but I know it doesn't make sense at all, I think the pain is just getting to me too much.
I'm an atheist and don't believe in ghosts, demons, angels, or any sort of "supernatural" phenomenon/being.
I don't remember not being here prior to birth, and I suspect it will the same after my death.
I like this point, about it just being the same as before birth.
Do you feel like talking about your experiences?
I have a lot of experiences, too many to write the details of here haha, but I'm actually starting to write them all down now and hoping to maybe send it to some magazine or YouTube channel so if that ever happens I'll post a link here if I remember to lol!

But me and my family grew up with random hauntings, there would be a period of a month or so every year where a lot of things would happen and then usually stay quiet until the next year. Most things were minor but here's a few things I can think of right now,: lights purposely turning on and off seconds a part repeatedly (if that makes sense), noises: voices (usually of my family members when I was home alone), laughing, walking, running, rummaging. Things moving within seconds, scratches, something horrible happened to my pet (don't think I wanna talk about it in detail though), answering questions (in a way - hard to explain), doors unlocking, orbs, then there's full on creepy things like my mum (and my cats lol) seeing a black figure float across the bathroom, my nan being pushed down the stairs, doors slamming, faces, something even floating and then dropping and smashing everywhere. I say it in past tense but we still get it every year, just not at this moment. We don't get help for it because my mum doesn't believe it'll work, she believes exorcisms are satanic lol (she's a Christian but their specific religion doesn't do that stuff). Sorry this is long but thought you might be interested lol
Beliefs are that way, what we feed it grows. Personally, I am not even sure we can die in a sense nothing is after body goes, yet I am not worried what comes after, just as long as I am able to be fully present during the transition or whatever that would be. What has got you leaning towards believing in demons and ghosts vs. God?
I lean to believing in demons (and maybe ghosts - but that's just a fear mostly because of the whole pain thing) because I've had experiences with them, but I don't really believe in God because I've never had any experience or obvious proof like I have with demons.
personally I believe in god but not religion. if you believe in demons then the flipside of god must also be true. and ghosts may be beings that have unfinished business and until they let go they remain a ghost, that's my opinion. and I don't think we carry our pain over, unless we go to a real warm place lol. and
@Lara_C is right, try to deal with your issues so you can concentrate on having a good life now. mike
My solution to believing demons but not God was that maybe demons are actually just creatures like us and animals but they're just very different lol or maybe that they're energy, or energy creatures? Haha, just some theories, I don't think about it too much I just go by what I experience.
Thank you again everyone, I like your advice, they're good points and I feel less worried now.

(sorry for the extremely long post!)