I totally have those feelings, my first granddaughter moved in with me and my husband with her mum and dad at 1 month because of Covid and they just left after 11 months ? I saw her every day and helped for hours looking after her and more recently playing and we both developed a real huge bond. I am grieving, sad , missing her So ! Way more than missing my son and DIL . I feel like I let myself get too bonded, it hurts so much now , but I couldn’t help it it’s Covid and everything is exaggerated I’m a naturally very maternal person , and worry now whether she will forget me as she’s only 11 months. So an older child will always have a natural fondness for you , even if things change it will be gradual I’m sure ! Enjoy the time you have, it’s a gift , be in each moment and push the future worries away!