if you have to fit a Macbook that kind of defines the minimum size of the bag and makes it large for the small amount of camera kit needed. If its an 11 inch Macbook that really helps as you could look at a Lowepro Photo Hatchback which is a great bag for a small camera kit, small laptop or tablet and extra stuff.
The Lowepro Fastpack/Video Fastpack bags are good for bigger laptops as they have a large laptop pocket, main camera section and a top compartment for extra photo stuff or anything else you want.
For this fairly small amount of stuff and its light weight, I would find a shoulder bag perhaps easier to use and more secure as its simpler to bring to the front of you and access gear without taking the bag off. There are tons of choices such as Tenba Messenger, Ona Brixton, Lowepro Messengers, Think Tank Retrospective etc.
