re: Am I calculating my taxes right?

Door Dash is the independent contractor to the restaurants. You are technically an employee of Door Dash if they make all the arrangements of your deliveries.

You should talk to an attorney about your status. You need legal advice about financial risks you may not aware of. What happens if you get injured while on a delivery run? Your insurance may not cover you if it determines you were injured on the job since workers' compensation is the appropriate insurance for your injuries.