You are obviously thin enough to see your ribs! I wish
Variations in the body are completely normal. I have a large lump on one of my ribs close to the sternum just under my neck and only found it once when I lost alot of weight and was thin, I rushed to Dr and of course like you was told it was just a bony spur and completely normal.
Women have breasts different sizes and shapes, etc etc the list is endless.
Have you ever seen a osteopath,physio type person as they will be able to tell you if your posture is not good and this is causing your body to be out of line??