Tummy grew bigger once postnatal massage ends

I am so down and demoralised whenever i look at my body. I gave birth 8 weeks ago via emergency csect. I am stuck with this tummy. Like 3-4 months preggy. My tummy went a little smaller, and waist shrunk to 76cm during/after postnatal massage and i was so happy. But after a week or so, maybe because my appetite has came back and im in a better mood, my tummy somehow grew bigger back and my waist has went up to 80cm. I am petite and slim, but i have a big tummy😣 i dont know how to slim it down. Do i really need to diet and exercise ? I do not have diastasic recti, as per gynae mentioned. But somehow this tummy just wont go away. Any tips? #firsttimemom