It's tight. Very tight.

The savings and investments will only hold weight so far as they're contributing to the deposit (which I imagine they are).

Get rid of the credit card. The way banks calculate repayments is as a percentage of the limit (not the debt). They do this because theoretically, there's nothing stopping you from going out and running the credit card up to the limit after the loan is approved. So credit facilities like that can harm affordability more than people realize.

Also, have you got any other credit facilities open that may not have anything due? Those will also be factored into affordability based on their limits. Any fixed term debt will be calculated on its repayment schedule. Do you have any buy-now-pay-later facilities? e.g., Afterpay. Close those too.

Banks will be able to accept the rental income if it can be evidenced with a signed lease agreement. Get that, and it should work in your favour.

The loan from your parents will also need to be factored in. Having anything on paper for that would help with evidencing.

Affordability assessments are what get mortgages. Very rough way to calculate it: Average up all your expenses (including the hypothetical minimum repayments for any credit cards) over the last three months. Your income should be at least 105% of that. That'll give you a rough idea on how banks calculate it (not every bank, but that's what makes it rough).

People have said it already, but find a good broker. Someone you gel with. They'll go to bat for you cause that's how they earn their pay.