The scenario that you outline in your question is medically impossible! If you were 9 months pregnant, there is no chance that the ultrasound overlooked the fetus. Some home (urine) pregnancy tests are not reliable and can produce false-positive results. Blood pregnancy tests are more specific and exact than urine-based (home) pregnancy tests. Lack of period (menstruation) is the first sign of pregnancy but can manifest during other conditions, too. Intestinal movements can be easily considered as fetal movement by women who desperately want a baby. I recommend you to visit another gynecologist for a second opinion and to repeat the tests.