I'm about to give up my organic balcony gardening experiment. This is a cry for help.

Okay, just from the pictures, let me say what I think is happening:

1. You're growing too many different kinds of plants in a small space.
2. You're growing Cannabis, which draws literally every sweet-sensing pest.
3. Those things on the underside of the leaves you posted are Ladybug larvae, and they are GOOD.

You clear this up in about a week with a few simple things:

1. Get a clutch of ladybugs from your local nursery or plant stores. This should be available almost everywhere in the US.
2. Although I don't want to advocate for this because I love local pollinators, get a pheromone trap for the stinging insects. They cost about $10, and don't lure honeybees, but WILL kill local carpenter bees and yellow jackets.
3. For the aphids, get a soap-based spray, or make it yourself. It's pretty much just dish soap and water, but there are guides online. Spray EVERY MORNING AND AFTER SUNSET. This plus the ladybug clutch will make quick work of the aphids.
4. I see you have Basil in containers, move that AWAY from the plants that are infested with scale or aphids.
5. Depending on where you live, your nursery's may sell Mantids. Get them. They are beneficial, but ruthless in eating and killing anything in their grasp, including wasps.
6. If you have wasps around, there is a nest nearby. Inspect your building awnings, trees, or under anything shaded and find that nest. It's not two doors over, it's within 100ft of where you got stung. Find it, set a pheromone trap around your plants (not where you think the nest is), then after a lot of them are dead, go find and remove the nests next.

Don't leave standing water around, and make sure that you stay on schedule with the soap spray. Most of this will be cleared in just a week.

Edit: also for the slugs and stuff, you're growing a lot of stuff in a mostly shaded area, so you're just asking for slugs. Line a general area around your plants with Diatomaceous Earth. It's cheap, easy to use, and doesn't harm anything that doesn't crawl. Also, organic.

Double edit: DO NOT spray this black bugs with the striped butts. Those will be ladybugs soon that eat all the aphids. They are good.