You described a period of weight loss
after your pregnancy. It is important to identify whether the weight loss or weight gain is intentional or not. Did you exercise or eat less during this period that led to your weight loss or did you lose weight with no changes in your lifestyle? Your weight loss could be benign but it is important to see your primary care doctor
to determine if your weight loss is due to a medical condition such as thyroid disorders for example. Your primary care doctor can examine you and do basic lab tests to ensure that everything is in order. If there is nothing abnormal, it could be helpful to speak with a dietitian or nutritionist
about your diet. Weight gain should be accomplished slowly over time. Protein drinks are used by body builders often to supplement their diet. The protein drinks are soluble protein that are easily excreted by your body if you do not use it. In order to take advantage of the benefits of protein drinks, you could do weight training exercises that stress your muscles. Your muscles use protein to build upon itself. Other methods of weight gain is to simply eat more calories than usual. If you eat 2000 calories a day, try eat an additional 200 calories per day. You can keep a chart and ensure that you are gaining weight appropriately and in the places you desire. Please discuss with your doctor.