I am not sure there is evidence here that the bike is too large. People often put their saddle too low and feel that they should be able to touch the ground without getting off the saddle, which is wrong. If the bike was bought for you, it is presumably of the right size. A bit off size is easier to tolerate with women's than men's frames. Within steel bikes, and even within all, Trek 720 is an excellent choice. I would not give up on it.