Bearer Size & Wood type for Skillion roof

To anyone helpful that may be able to assist,
I'm building a new shed 4.4mW x 7.5mL, concrete floor is poured and single leaf brick walls are up. I decided on a Skillion roof (possibly a mistake) with high side at 3.1m, low side at 2.4m and a span of 4.4m.

Can't wait to 'move in' but no one can give me definitive advice on what size rafters I should be using. With the eave I'll need lengths at least 5metres and based on recent efforts it looks like I'll struggle to get jarrah in that length. I'm resigned to using pine if I have to but I guess it's a lot lighter.

Does anyone have any idea what size pine rafters I should be using and at what distance apart.
If I managed to get hold of Jarrah can anyone advise what size jarrah rafters I should be using and distance apart.

Any positive feedback would be greatly appreciated.
Cheers,
DJA