Why cant you just put your old stuff on n a pool? That will give you a start. You don't know just how much muscle or fat was lost. You can hang your rig on a pool orm a scale and find the buoyancy. If neg 8# then you in your suit was 8 light. Work from there. Put your old suit on and get in the pool and weight to get neutral. You will know by that weight how much your buoyancy has changed. Until then you done know what changes you need to make. Perhaps a new wet suit will do it. From what you said you have lost mass and lost muscle. they counter each other.