Nextcloud Docker Storage Difficulties

I have been trying to set up Nextcloud on docker and I have been having great difficulty trying to get it to play nice with my external SSD

I install it with

  nextcloud:
    image: nextcloud
    container_name: nextcloud
    restart: always
    volumes:
      - /media/usb0/html:/var/www/html
      - /media/usb0/data:/var/www/data

    environment:
      - MYSQL_PASSWORD='REMOVED'
      - MYSQL_DATABASE=nextcloud
      - MYSQL_USER=nextcloud
      - MYSQL_HOST=mariadb
      - NEXTCLOUD_DATA_DIR=/var/www/data
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.nextcloud.entrypoints=web,websecure"
      - "traefik.http.routers.nextcloud.rule=Host(`REMOVED`)"
      - "traefik.http.routers.nextcloud.tls=true"
      - "traefik.http.routers.nextcloud.tls.certresolver=letsencrypt"
    ports:
      # The HTTP port
      - "880:80"
      # The HTTPs port
      - "883:443"

it sets up and installs
there are files going onto the HDD but it still seems to be taking up space on the sd card

Tristan@Docker:~ $ df
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/root       30388284 9034140  20085744  32% /
devtmpfs         3834560       0   3834560   0% /dev
tmpfs            4000256       0   4000256   0% /dev/shm
tmpfs            1600104    1228   1598876   1% /run
tmpfs               5120       4      5116   1% /run/lock
/dev/mmcblk0p1    258095   30520    227576  12% /boot
/dev/sda1      976759804  648468 976111336   1% /media/usb0
tmpfs             800048       0    800048   0% /run/user/1000
Tristan@Docker:~ $ Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/root       30388284 9034140  20085744  32% /
devtmpfs         3834560       0   3834560   0% /dev
tmpfs            4000256       0   4000256   0% /dev/shm
tmpfs            1600104    1228   1598876   1% /run
tmpfs               5120       4      5116   1% /run/lock
/dev/mmcblk0p1    258095   30520    227576  12% /boot
/dev/sda1      976759804  648468 976111336   1% /media/usb0
tmpfs             800048       0    800048   0% /run/user/1000

and the system tab seems to agree
Screenshot 2022-03-01 173238

also, it won’t log in with firefox for some reason
any advice would be much appreciated

if any additional info is needed just let me know

i don’t know if it makes a difference but I’m also running traefik as you can probably tell from the lables