D.P.
Dear R.,
Sounds like your daughter doing just fine, first of all if you breast feed her she dosen't need anything else untill she is ready for her solids. Formula is only substitute, you don't mix it with your breast milk which is the best source of vitamins and nutrients for your baby. Don't worry about her short naps either, remember every baby is different and also 40 percentile is great too. The thing that she is putting everything in her mouth, that is completly normal, that is the way babies explore the world and on top of that she might be teetheing. Since she is 5 months old you could slowly introduce her to solids already, like rice ceral. Good luck and don't worrry you have healthy baby. And try to ditch the formula.
Dora