Is it advisable to ring sling a toddler? My 13 kg 2.5 yr old always gives me a shoulder ache when I sling him. Wondering if he's too big already.

i feel that it is too heavy to sling a toddler of that weight. You are putting pressure on your shoulder and neck. You might consider a hipseat that is not so straining on your shoulder and is comfortable for both. Otherwise, do consider a stroller where he can sleep more comfortably and you don't feel the strain.