I think the remote option needs to be uppercase for starters. Also this opens up ssh access to your work host to world. You can limit this to localhost on your DO vm with:
sudo ssh -n -R 127.0.0.1:8022:localhost:22 firstname.lastname@example.org
The following command then would be
ssh -o ProxyCommand="ssh email@example.com nc localhost 8022" companyusername@companyofficecomputer
You need netcat installed on the DO host obviously.