Just got a new mobile and it's too big to put in my back pocket. I've never really carried a handbag during the day, but think need to get one. I would like a cross body one so won't fall off shoulder when children tug at hands, and I dont want a big one- just big enough for keys, phone and purse. I would also want it to be pretty plain. I've browsed a bit and not seen anything I like. Any suggestions?