No, wearing eyeglasses won't cause flat or crooked nose. But if your eyeglasses are too heavy, it may cause indentation on your nose after several years of wearing glasses. So, one shall buy light weight eyeglasses frames. For this consideration, you can choose titanium glasses frames, memory plastic glasses frames, half rimless glasses frames or rimless glasses frames so as to care to your nose.
Generally speaking wearing too much won't change your nose shape. The total weight of the frame glasses and the glasses on your nose will press your nose and make your nose a little pain if you wear your glasses too much long, but it doesn't matter. It won't harm for your nose. If you still a little be care about it, you can choose a pair of light-weighted frame glasses, such as the material of pure titanium, B Titanium. Moreover, you can choose a pair of glasses with Nose pads. At last, you can choose contact lenses.
Wearing glasses too much can change your nose shape. When you wear glasses for a long-term, a certain range of both sides from eyes to nose may be pressed and appears flat. After you take off your glasses, the whole range of eyes has not the outline which it should have. But when you wear glasses, the glasses can fill the flat part, and you do not feel the change.