My son was like your daughter - fully breastfed with solids at 4 months on. He always had the looser stools of a breastfed baby. Our daughter was formula fed for medical reasons, and she always had looser stools, too.
We're actually battling encopresis right now (her holding her feces in). She'll be two this weekend, and we've been battling it a few weeks now.
Solids will firm-up the stools a little bit, but if you begin to see that they're really dry, I'd call the pediatrician (I'd also suggest asking at your next well-baby visit). You may need to offer more fibery foods to alter the consistency.
Isn't it amazing what we'll talk about as Moms that would have been taboo a few years earlier?