I'm pretty sure neither the backpack nor the shoulder bag will be the real problem. There are a number of things you can try to do or avoiding doing, so has not to draw attention.
Don't carry any purses that do not close 100%, nor any purses that leave big gaps in the flaps, for example. Avoid purses with long shoulder straps, the closer to your body the better.
Like Linda said, Its best to use bags that have a good zipper and if possible that it has some type of carabineer to ensure it's closed.
If you only need to carry your money purse for example, place it in side your front pocket, not your back pocket.
Don't carry more money or valuables than absolutely necessary, try not to wave money around in public places and....ect ect.
You can go on and on, but this is the first thing that came to my mind. I’m positive other MM members can give you better pointers from their personal experiences.
Enjoy your stay