At 29 years after being mother your weight is extremely stabilized.
After delivery was the best time to increase the weight, but now it would be difficult without strenuous exercises.
Go for High intensity Exercises with high whey protein diet. This helps building muscle to improve appearance but marginal increase in weight.
If feminine features are low, then don't go for exercises. You may be required to See gynecologist to assess your female sex hormones especially estrogen.
If you are genetically like this nothing much you can do except some temporary relief.