Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned that you are fat when everyone else says otherwise.
With the information that you have given, your Body Mass Index or commonly known as BMI calculates to about 22 which is within the normal limits of 18-25. BMI is the commonly used indicator of obesity.
You must see a psychiatrist for help as inappropriate feeling of being fat is part of eating disorders symptom complex and shall be thoroughly assessed by a session with psychiatrist to rule out eating disorders like bulimia and anorexia.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.