May be helpful, from the wiki, "The slime chunk algorithm in Bedrock Edition is different from in Java Edition. The algorithm doesn't depend on the world seed, thus the chunks that slimes can naturally spawn in are the same for every world."
Slimes also spawn in swamp biomes at night and the wandering trader will sometimes sell slime balls if you're looking for alternative ways of getting slime balls.
I was playing Bedrock for several months before I found a slime. Bedrock (de)spawning is pretty broken, so they're probably not going to show up if you're near the mob cap. Best thing I can suggest -- get underground (can't remember what their height limit is), keep switching to peaceful and back, and keep your ears open for a squelching sound. (Or you could use code blocks to kill all the non-slimes, if you're into that). There's quite a few slime chunks around (1 in 10, I believe). The problem is other mobs never despawn.
Best bet is to go to a swamp biome when the moon is full. I was having a hell of a time getting enough slime for a project I was working on. I think it helps to torch the caves within the area around the swamp when you are hunting for them.
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See my Minecraft world (100% Survival), Dirty Baker City here:
The Meaning of Life, the Universe, and Everything.
I have come across slimes in caves with my Bedrock world, but I didn't have any luck trying to spawn them in a slime chunk. However, I've got a couple stacks of slime blocks from a nearby swamp where I did some basic flattening to increase spawn rates. Looting 3 sword helps a lot.