I've had stool with blood in it for a four years I was scared to get it cheacked outbut, do I have cancer now?

Go to dr. There are many causes of blood in stool that are not cancer. Some are as simple as hemorrhoids that you don't know you have to a list of other things. One thing, blood in stool is not normal & something is wrong and you need to know what it is and get it under control . At 14 it would be most unlikely to be cancer but could still be serious. See dr soon.
See doctor. At age 14, unless there is family history of early cancer, it is unlikely that you have cancer. However, you should definitely see a doctor to find out the cause of bleeding.