The symptoms you are having sound like a potential iron deficiency and thyroid imbalance. I suggest that you start taking a micronized, microencapsulated iron pyrophosphate III supplement 2 teaspoons (30mg elemental iron) per day. Low iron [1] is common in breastfeeding moms and you will end up bald if it is not treated. It can also cause weight loss and panic attacks. Request that your TSH be tested to rule out any thyroid issues. You will want to ask to see your results. Your TSH should be between .5 and 2, higher than 2 and you may have a low functioning thyroid. If it is under .5 you may have an overactive thyroid and will need to work with your doctor. In addition, have your ferritin and hemoglobin tested. Ferritin should be around 70 ug/L, and hemoglobin should be around 140 g/L.
Make sure you are eating enough calories and getting enough protein every day to support breastfeeding. Roughly, breastfeeding women need to increase their daily intake by 500 calories. Continuing with a prenatal supplement while breastfeeding is a good way to make sure you are getting essential nutrients.
To help support your adrenal glands and easy anxiety, I would recommend 280 mg of elemental magnesium bisglycinate or threonate daily.