BMI isn't a scientific measurement, it's a general average to compare to. There are more factors to your body style than "height" and "weight" such as muscle to fat ratios and bone structure. My family is dutch/irish so I have big bones (as cartman would say). Many people guess that I'm 170-180lbs but I actually weigh 220. According to my BMI, I'm not just overweight, I'm mid-range obese. I do not look obese.

Basically just try to keep in mind that BMI doesn't really mean much and you're not "officially" overweight. Only a doctor can make that sort of diagnosis. Best wishes.