How do you ask to hang out with people without annoying them

Ive been feeling pretty down and I overheard a group of my friends planning to meet for lunch. The thing about these people is that I feel like theyre only really my friends because I sat with them back in high school 4 years ago. But they never invite me to anything or message me first and maybe I'm imagining it but I feel like they dont even like me.

I dont really want to make them invite me out of pity or whatever and ruin their hang out. But I also dont want to be alone.

I'm trying to figure out how to ask them if I can join without making them uncomfortable basically