Over Weight

Everyone but mostly my mom keeps telling me I'm still very fat. I had my 3rd child back in May i gained 15 pounds and before leaving the hospital i got on the depo. I dont know if thats why i cant lose the baby fat but ive tired a few diet and try to work out whenever i get a chance i work and when home i got my 2 youngest and my toddler need 4 eyes on him at all time. My mothers calling me lazy because I'm always tired and prefer to nap when the babys are napping because when they're up I'm doing house chores and chasing my little tornado. Please someone tell me how they lost they're baby fat. Im 5 feet and i weigh 148