Advise needed!

My baby is a 6 month old premie. He is amazing but he will not sleep unless he’s being held by me. He can’t be anywhere without being able to see me. Whilst I love our bond I’m finding it incredibly difficult as I have 2 other children (7 & 2) and I can’t get anything done especially once he’s asleep on me. I need to start getting control over this as he’s just as restricted as me because he needs me to sleep properly. Problem is I have no idea where to start as my 2 year old is in our room still and neither of my other 2 babies were quite this attached. I feel like I’ve made him too mummified? Everyone tells me I hold him too much but I respond to my children’s prompts so I don’t really understand what I’ve done wrong?