Super exhausted each day but not losing weight!!

Hey guys, my little one is 4 months and I lost most of my pregnancy pounds in the first two months, but I've been eating clean and taking care of the baby all alone ( which is super exhausting, hubby helps for 3 hrs maximum in a day) and breastfeeding and haven't lost any weight in the past two months. My body is fully drained end of every single day and I wake up in the night to feed the baby,

Why am I still not losing some pounds? It's surprising. ( No time to workout/ I take the baby for a walk sometimes, like 4000 steps)