In middle school and the first few years of high school I was very skinny naturally but my weight has crept up a bit the past year and a half or 2 years. yes, I've grown so naturally I've gained weight that way, but my BMI/body composition has increased as well. I have tried paleo in the past with no change in weight. Because it's summer I'm really getting my butt into gear and for the past two weeks I've been using the myfitnesspal app to track my food intake and it usually comes out into even thirds of fat, carbs, protein and my weekly average for calories per day is 1250. My workouts have been patchy, haha. I know I won't see abs until I lose some weight so that's what I'm focusing on right now. I'm dying to wear high waisted shorts and crop tops with confidence!!
First, I agree with the others - health-wise, that doesn't seem like a concern to me.
Second, I have to say that your posture seems to be part of the problem (not that there actually is one). In that picture, you're leaning back just slightly. But more problematic is the anterior pelvic tilt and excessive lumbar curve. In other words, you're sort of sticking your stomach out.
Try this: Stand tall. Make sure your ears align above your shoulders. Level your pelvis. Let your hands hang down by your sides. Ask a friend to take another side picture. You'll probably like what you see better this time.
I am only going to give advice because I am pretty sure you are going to do something whether we tell you to or not.
Lift some weights and run some sprints.
Go for the 'unwieghed, unmeasured' paleo technique. This is not a weight loss issue. You already look great and if you want to improve, you need more muscle mass- all over, not just in the ab area. This means you will need to eat more, not less.
Remember to give your muscles rest days- muscle growth happens on the rest days.
Do you know your body fat percentage? Have you done a pinch test? To be honest your body comp reminds me of me several years ago. It's the body of someone under stress- flat chest, poochy belly. Are you on hormonal birth control? What is your omega-3/omega-6 ratio like? What I would recommend is a super-high quality diet and don't even bother with workouts at all. It's not your abs that are the problem, it's body fat and the distribution of body fat. HArd workouts = more stress. Take a walk in a nice park instead or take a gentle yoga class. Eat liver, good grass-fed butter, fresh berries, roe, good quality fish, etc.
As for low-carb or high-carb or whatever, I never worried about carbs and have a flat stomach and B-cup breasts now. And I've maintained it for two years now without even thinking about it. Not many people who worry about macronutrients can say something like that. Also, many of the people here who say low-carb is the best/only way are older and have different hormonal issues.
I've always had that pudgy spot as well. The only thing that ever flattened it completely was swimming an hour a day for 2 months when I was 21 yrs. old (breast stroke). I looked amazing! Now that I'm 41 and have been pregnant, I'm not sure if that would work anymore...