There are a few ways that you can get an idea of what it is. First, how old are you and how long were you overweight? have you had kids?
Does it droop down and hong off your body forming an "apron"? (stretched out skin but maybe some fat there too) When you pinch a fold between your fingers, how thick is it? Can you pull it away from your body?
Unless you are very muscular or extremely heavy boned, have very muscular legs or big boobs, at 5'3" and 139 pounds you most likely have some excess fat on your stomach.
I doubt that we could really tell from a picture, and I wouldn't advise post it anyway

If you belong to a gym, you could ask to have your body fat measured, or a doctor could tell you.
I maintained at 135 for about two years before I bit the bullet and lost down to 120. Those last 10-15 pounds made an enourmous difference in the way I looked. Healthwise, probably not much of a difference- but I call those the vanity pounds. They make a big difference in the mirror and clothing. I'm just a smidge under 5'3".
Congratulations on the weight that you have lost!!
Mel