Need help with pouring small concrete slab

I want to pour a slab of concrete next to an existing one in order to make additional room for a storage bin.

By my calculations it looks like i will need 10 cubic feet of concrete.

Can I do this by myself? Setting up the area (2x4 frame, concrete joint pad, gravel, wire mesh) doesn't sound like a big deal but what about the concrete?

My calcs tell me I need about 10 cubic feet of concrete which translates to 17 bags of sakrete or quickrete, i don't need/want the quick set type.

I can rent a mixer but that only mixes 2 bags at a time. Do I have time to mix 17 bags 2 at a time to pour the concrete in place or will it harden unevenly all over the place and make a big mess?

Thank you.

Edit: Here's a sketch of the slab. It's an odd shape: http://ift.tt/1CQX2lu

Submitted January 30, 2015 at 03:56AM by ser_zone http://ift.tt/1zaakIE