Yes, that is what saint Paul said and I think it applies to the Blessed Virgin Mary too. Her suffering made up what is lacking in the afflictions of Christ on behalf of the Church. Remember what saint Paul wrote? Colossians 1:24 KJV Who now rejoice in my sufferings for you, and fill up that which is behind of the afflictions of Christ in my flesh for his body's sake, which is the church:
What disturbs you encourages me; it is an encouraging thought that the Blessed Virgin Mary prays for me, intercedes for me, and seeks blessings for me as she does for all the faithful who are her children because they are the body of her holy Son, the Lord Jesus Christ.