IELTS should have been taken before you sent in the application.Although you don't need to send in the IELTS test result along with the application at Sydney NS. But if you have evaluated yourself at high proficiency and gave yourself 16 points but at your local Visa post if you are unable to prove it and submit the supporting documents, you can be inadmisissible for mis-representation under Sec 40(1)(a) of Immigration and Refugee Protection Act.
I am Just a Student and becoming a Consultant . So, I can't be giving a legal advise but this is something I am repeating from the Act. For further information please refer to IRPA or CIC.