Hi, there,
It can be really difficult. Childbearing tends to alter our shape - forever. I am personally a bit dubious about the concept of "getting one's body back". It's really never going to be the same. It is normal to breastfeed for 2 years or more. I wonder what you can do to help your body without weaning? Can you get time to excercise more, stregthen your body? Can you (if you don't already) make sure you get really well fitted bras? Can you see a physiotherapist or chiropractor for advice on posture etc? Is your older child ready to wean at all, with some gentle encouragement? Thant could make a difference - or you could at least see what would happen if you were "halfway" there.