osteoporosis in women under age 50

Dear Dr. Schulze, I am a 48 year old woman. Recently I was told by my doctor after having a bone density test, that I have osteoporosis. I am only 4'11" tall and I weigh 141 pounds. I would like to know if this is common in women my age and is there a way I can reverse the damage to my bones? My doctor recommended 1500 mg. of calcium a day along with 400 IU of vitamin D, and exercise. I am also taking Miacalcin in a nasal spray. I don't eat any dairy but I do drink soy milk with calcium and vitamin D and I eat plenty of vegetables and fruits. Any information you can give me would be very helpful. thank you. Valerie Dunbar