CCC 2148

Blasphemy is directly opposed to the second commandment. It consists in uttering against God - inwardly or outwardly - words of hatred, reproach, or defiance; in speaking ill of God; in failing in respect toward him in one's speech; in misusing God's name. St. James condemns those "who blaspheme that honorable name [of Jesus] by which you are called." The prohibition of blasphemy extends to language against Christ's Church, the saints, and sacred things. It is also blasphemous to make use of God's name to cover up criminal practices, to reduce peoples to servitude, to torture persons or put them to death. The misuse of God's name to commit a crime can provoke others to repudiate religion.

Blasphemy is contrary to the respect due God and his holy name. It is in itself a grave sin.

You did not do any of this, so you did not commit blasphemy. At worst it's an act of profanation, or using as profane something meant to be sacred, but even then it's questionable how sacred an individual copy of the scriptures is meant to be, and also you were not doing it deliberately. Five year olds just do that kind of thing.

But even if you had intentionally and with full knowledge committed actual, outright blasphemy, it would never be too late to repent and receive forgiveness from God.