If you haven't been sick in a year, ex. fever, cold.. does it mean you're healthy?

More or less: At your age, you are healthy if there are no symptoms. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Drink enough water daily so that your urine is mostly colorless. Practice safe sex. Get HPV vaccine.

No but: Some diseases may not cause symptoms until the late stage- you must heard of otherwise healthy people who have a heart attack while jogging. Certain cancers may take months or years to cause symptoms. On the other hand, in the absence of any strong family history of cancer and feeling good otherwise, I won't lose sleep over it especially at your age. Enjoy life.