A while ago, I was searching for something exactly you're describing. Something that I can carry in the front, roomy enough, and not too hot for either of us.
I bought Global Pet Hipper (
http://www.amazon.com/gp/product/B00...lance&n=284507)
after looking at several carriers.
You can actually adjust this so that you carry the pouch right in front of your tummy. I've carried her in it and she's quite comfortable. It has mesh pockets on the sides, and front so you can also carry her/his food and water.
Amazon's offers the best price, as far as I know. I checked out several retail stores and they're all pretty over-priced.
Anyways, check it out.