What was her stool frequency before starting on semi-solids? From your description, she just started taking a bit of semi-solid, is on breastmilk, and stool looks fine, does not seem like typical constipation.
Before my fully breastfed boy started solid, he poo-ed once every 3-10 days. This is normal for bf-babies. He accepted semi-solids very well at 6.5 months and ate brown rice cereal, veges & fruits initially. Poo frequency gradually increased to once every 1-3 days. When stools show some hardness, I offer him more steamed pears / peaches / plums / papaya. This usually helps.