Here's my 2 cents worth: as women, we seem to rely on bike mechanics more than men, which is OK but when it comes to simple stuff we really need to be more empowered to know what is going on and how to fix it. In this case, you don't need a new mechanic or a new bike but just new knowledge -- all bikes flex when you ride them, it is how they are made. That is why a chain can be perfectly quiet on a stand but rub a bit when riding. When riding watch where it rubs -- front or back -- and at what gears. Can you trim to fix? Did you cross chain? If not, learn which adjustment screw works for high and low gears on both your front and back deraillluer and how to adjust them. Take a small screw driver with you when you ride and using your adjustment screw knowledge, turn the correct screw the correct way (usually no more than a quarter turn) and you have mechanically and independently fixed your bike!!