Postpartum weight

I just had my third baby 4 months ago. I am exclusively breastfeeding and I haven’t lost not even a pound. Backstory, I am a SAHM and I am currently in Graduate school. At my internship I am always sitting and at home I’m doing homework, making dinner, or doing things with my family. I haven’t eaten out in almost two months, I eat eggs every morning, I have at vegetables and fruit and protein. I’m trying so hard. I know I need to be more active, any advice? I need it! Thank you so much!