According to the Rite of Baptism for Children, water may be done by pouring water over the child, or by immersion.
Speaking of the celebrant, the rite says:
"He baptizes the child, saying:
N., I baptize you in the name of the Father,
He immerses the child or pours water upon it
and of the Son
He immerses the child or pours water a second time
and of the Holy Spirit.
He immerses the child or pours water upon it a third time" (Rite of Baptism for Children #60).
Since “to immerse” can mean to cover up but could also mean to simply dip, and since the Church could have used the word submerge but did not, you can be assured that the fact that your daughter’s head did not go under the water does not invalidate the validity of the baptism.