Yeah, so I don't know if Australia is in anything like America, but if it is, you aren't actually employed by that company.
You employ yourself.
Even your contract spells out the same pitfall that exists in America: You have to handle all of your own taxes, even the ones that normally your employer would be paying. If this were America, it would mean not only that you have to do all of the math and calculations yourself as well as setting aside the money on your own, but it would mean you would have something around double(?) the tax burden.
But it also means that you work for yourself. You'll also note that there's a line in your contract that's specifically says you don't only work for them. Which means they expect you to be working for other people in addition to this company.
And they're asking you to match or beat the output of a company that has actual employees, plural, with a background in software engineering working on the same concept?
The owner of the company you are contracted with has unrealistic expectations.
At this point though, I have to say that contract work is completely outside of my wheelhouse.
Everything I've said has been with the assumption that you were an employee, and apparently you are not an employee.
I have no way of knowing whether or not there is a clause in your contract that would penalize you for quitting.
I have no idea if your contract has delivery requirements that you must meet.
I have no idea if your contract says that you will face financial penalties for failing to meet deadlines.
And I have no idea if Australia requires superannuation pay to be given to contractors. It may not.
In fact there's another line in that contract that specifically forbids you from portraying yourself as a company employee. Which kind of makes me feel like you're just a single name drop away from violating the terms of your contract here in this question, since you've been saying this whole time that you were an employee. Apparently by mistake.
Maybe someone else here has more expertise. It might be worth starting a new topic where you say something along the lines of "I'm in Australia and I misunderstood my employment relationship, and it turns out I'm a contractor. What do I do?"
But it really does feel like you need to go over all of the terms of your contract very carefully and start researching what some of the terms in it mean. Because I get the feeling you don't actually know what's going on with your career.
I'd hate to think you didn't take care of all of the proper taxes last year and haven't been planning for proper taxes this year, because it might mean you're a year and a half behind on actual taxes.