At 22 years of age, your risk for breast cancer is very very very slight- less than 1 in 3000.
Many women have cystic breasts- to varying degrees.
They can be painful if pressing on a nerve, or your breasts are tender prior to your menstrual cycle. The ultrasound distinguishes fluid from solid, so as long as none are solid, you can rest assured that you most likely don't have cancer. Cysts don't increase your risk for cancer either, but sometimes they need to be aspirated due to size, location, or appearance. Some women find that avoiding caffeine, salt, and chocolate helps decrease cystic breasts and discomfort. I can understand your concern and anxiety.