Docker run on loop in bash script?

Question

I am trying to run a number of containers (custom image) equal to the number provided at the command line when running the script. I suppose I could use swarm too but figured this would work too and might be a better user experience if I distributed it (I don't know).

The script I have so far:

#!/bin/bash

docker build ./client -t python-mqtt-client

while getopts ":n:i:f:" opt; do
    case ${opt} in 
        n ) number=$OPTARG
        ;;
        i ) interval=$OPTARG
        ;;
        f ) format=$OPTARG
        ;;
    esac
done

echo ${number}
echo ${interval}

for i in {1..${number}}
do
    docker run -d --network mqtt-demo_default --name py-mqtt-client${i} python-mqtt-client /mqtt_client.py --interval ${interval} --format ${format}
done

It only seems to spin up one container each time I run it even when I run it with n > 1...like script.sh -n 5 -i 1 -f json

For reference, here's the Dockerfile that creates this image:

# syntax=docker/dockerfile:1
FROM python:3.8-slim-buster
ADD requirements.txt /
ADD mqtt_client.py /
RUN pip3 install -r requirements.txt
CMD ["/mqtt_client.py"]
ENTRYPOINT ["/usr/local/bin/python3"]