First thing first, are you sure she is a she? If she was pregnant she would be taking it easy. A 3 inch red eared turtle is too small/young to be breeding. The fast swimming and jumping is either wanting to get out of the water or she is hungry. Does she have an area to get out of the water? When did she start this behavior? New tank? Water too warm? Did you add water conditioner to the water? Chlorine in the water maybe bothering her. Check with a good reptile store, the staff there can usually answer your questions.