I'm just using an Urban Originals tote bag. Not a proper nappy bag, but they come in beautiful prints and are HUGE, I fit all the kids stuff and mine. It has two side compartments where I put my phone and keys and another zip compartment on the other side. It also has two side pockets on the outside which I also use for keys etc at times.

Google Urban Originals and have a look at the website - although I must admit I've found MUCH groovier prints at a local shop that stocks them than I've seen online. I'm onto my second (sold the first one to a friend cause she saw it and loved it so much), it is red and has owls all over it. Luuuuurve it. You can also get matching purses.