Have you looked at your diet etc in regards to what you're eating and the calories you're consuming? I would add low volume foods, milkshakes etc and also seeing the GP to rule out anything else if your calories are sufficient.
As above. Consult with your GP. But take into account that breastfeeding can burn up to 500 calories a day so if you are eating like pre pregnancy, it makes sense you're losing weight.
I had the same happen to me, exclusively breastfeeding baby and I'm 10kg lighter than pre pregnancy, turns out it was my thyroid that's the problem, so like others have said, worth a visit with the gp for a check. Also our babies have the same birthday🙂
Are you sure it's breastfeeding causing this? Have you been to the GP to rule anything else out? Have you changed your eating habits?