I am 22 and scared i might have cancer i dont have any symptoms as far on and off constipation and consistency of my stool/shape i did a fecal occult test was negative . my stool has been looking narrower than usually mostly everytime i poop?

Cancer of the GI tract is rare in 22-year old females, depending on family history. However, you should consider having a complete evaluation by a gastroenterologist. There are a number of possibilities in regards to a diagnosis meeting the description you provide. A GI doctor would likely order other tests or procedures to narrow down the possible causes of your bowel issues.