It's fine, nothing's broken.
RNG is fine, the fact that you think you’re unlucky is either in your head or done to you by other players. You rolling <10 has nothing to do with Blizzards RNG because others roll >90, BiS items still drop, just because you see yourself in a perpetual string of bad luck doesn’t mean anything.
You're not special, do GDKP's.
Blizzard isn’t out to get you, you’re not special, if you really want to get the items you want without the RNG (other than the item needing to drop) then yes you should be joining GDKP’s. They’re by far the most fair form of loot sytem Classic has, if you don’t want to continue paying for your sub then buy tokens after you’ve done your GDKP. I haven’t payed for my sub since the token came to Classic in WotLK. You have too much of a cynical outlook on what might happen that you refuse to even attempt it, join a GDKP, make some gold and if something that you need drops buy it and if not well then at least you have more gold for your next GDKP run.
That’s what good about GDKP’s even if your loot doesn’t drop you still get something out of it.
Guild advice
I don’t know your guild situation but if you’re having issues with how loot is being handled then you should at the very least talk to the officers/guild leader about it. Don’t just let it build and build then you explode at them for what they’d consider not a big deal, if they’re not completly transparant with why X piece is going to Y person over Z person then you need to bring that up with them.
You’ve not described what kind of raids you’re doing or if you’re even in a guild but again if you’re always last on weapons and trinkets, arguably the most important pieces for most classes then you should find out why.
Wait on your servers Discord? So you haven’t tried at all in-game? Why not? Just message someone in-game and ask if they’re looking for potential raiders.