Is separation anxiety more intense with breastfed babies? My daughter is so clingy!

Yes, for my kids. I feel breastfed babies are more attached to the mother, due to the close bonding and touching during latching. However, I think other factors e.g. if you are the only care taker to your child, and she sees you most of the time, and below the age of 3 years old, the separation anxiety is even greater. But believe me, soon they will outgrow the phase and learn to be independent. Meanwhile, just enjoy the close relationship with your daughter now.