Look into IIFYM for breastfeeding moms.
Breastfeeding can cause the body to go into storage/starvation mode especially with surges in cortisol and even worse, if you try to "cut" calories. Im eating 2200 calories a day and losing almost 2lbs a week since starting. I also take vit c with iron, prenatal without iron, ashwaganda, and calcium/vit D liquid supplement.
If, after a few months there is still no movement, then look into having the thyroid checked. It can go haywire- either way- during pregnancy and post-partum.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5104202/
"Women who breastfeed require approximately 500 additional kcal/day beyond what is recommended for non-pregnant women.The estimate is derived from the mean volume of breast milk produced per day (mean 780 mL, range 450-1200 mL) and the energy content of milk (67 kcal/100 mL)....The recommended daily allowance for protein during lactation is an additional 25 g/day. Requirements of many micronutrients increase compared to pregnancy, with the exception of vitamins D and K, calcium, fluoride, magnesium, and phosphorus. As such, it is recommended that women to continue to take a prenatal vitamin daily while they are breastfeeding (Tables 2,?,3).3). Weight loss during lactation does not usually impact the quantity or quality of breast milk, but maternal deficiencies in magnesium, vitamin B6, folate, calcium, and zinc have been described during lactation.69,71 Both fat (vitamins A, D, K) and water-soluble vitamins (vitamins C, B1, B6, B12, and folate) are secreted into breast milk and their levels are reduced in breast milk when there is a maternal vitamin deficiency...