SJL - It must be so hard for you at the moment. I agree with what others have said - check out all of your options as you may be able to get some through centrelink. I am sure you already have but it might pay to check again. Do you have family that can help?
As for your parenting - you are just feeling down about it all but deep down I hope you know that you are being an awesome mum. You know what? She won't remember any of the things you are worrying about now. But she will remember the time you spent with her when she was sick and the fact that you are there for her when she needs. I am sorry that things are tough at the moment but they will get better. Big hugs.