My 18 months old baby has been passing light colored stools. Is it normal?

Hi doctor,

My daughter is 18 months old. For many months, she has been passing stools that are white or very light yellowish brown or chalky color. I have seen my GP in the past and with just a feel of tummy they tell me everything is fine. I feel there is something else and just cannot seem to settle. Her belly is very large considering she has such a small frame and feels this may have some part to do with it. When passing stools, she can often leak out her nappy because it is so loose. She has been on solid foods since she was 6 months old. She has full fat cow milk morning and night. When friends or family look after my daughter, I get comments of she done a dirty nappy, but it was really chalky. Is that normal for her? It is worrying me. She also holds her breath when worked up. This has happened since birth. It takes up to a minute for her to come round. Her tummy hardens and is solid throughout and then she projectiles. The doctors had seen this and just told me that breathing spells are common. But, with the way these bowels are, I am concerned whether this is related to. I am very stressed out and feel that I need a second opinion.