I breastfeed my girl (now 7-mth) since she was born. She is willing to be fed by bottle since she was 6-mth. Before that, she cried so hard and refuesed to drink.
I started to give her solid food when she was 6-mth and she is doing really good. She likes cereal and congee. I give her 2 meals per day and she can finish 1 bowl each time.
So I don't think it's a matter of breastfeed or not. Try to think of more variety of food to attract them to eat.