Can my tiny balcony support a DIY vertical herb garden with heavy pots?

I live in a third-floor apartment with a very small balcony - about 3 feet deep and 6 feet wide. I’m keen on setting up a vertical herb garden using some metal shelves I found at a thrift store, but I’m worried about the weight. Each pot I want to use is ceramic and roughly 3 pounds when empty, plus soil and water. I’ve measured the balcony floor and it feels sturdy, but I don’t know the safe weight limit, especially since I’ll have 3 shelves each holding 4 pots. I’ve tried searching online but most advice is for ground-level gardens or large patios. I’m hoping to keep the setup lightweight but also want the plants to thrive, so plastic pots don’t seem ideal. Has anyone done something similar on a balcony this small? How did you figure out if your balcony could handle the load? And are there any clever tricks to reduce weight without sacrificing plant health?