it’s strange what our “inner talk” can do to us. When I saw your post my first thought was “Thank god she’s breastfeeding” Oddly in this society where every day brings a new news story about the epidemic of obesity and diabetes - we spend all our time pressuring mothers to overfeed their babies and then spend the rest of their lives trying to slim them down. You are learning what generations of mothers have learnt before you - you can’t force a child to eat! (but thankfully, no healthy child starved themselves in the presence of food!)
Have you spoken to your doctor or health nurse - what do they say? On the face of it things don’t seem too far off track - you would normally expect babies to double their birthweight by 6 mnths and she looks to have done that. How often does she feed in 24 hours? Keep offering both boobs at a feed - you can spark that old girl back into action!) What kind of solids does she have? And how many meals per day? By this age they can have anything that the family eats - and should be having meat, cereals (not baby cereals, real cereals) vegies etc. And lastly, any history of allergies in the family? Asthma? Eczema? Does she have cradle cap? Does she have eczema? What about your other kids?