For behold, from this time on all generations will count me blessed. – Luke 1:48
Looks like you are not part of the family of generations that calls Mary blessed. You confuse devotion with worship. Mary was blessed because of the unique role she played in our salvation. This has nothing to do with worship. The Church distinguishes the devotion we give to Mary from the latria we give to God and God alone.
Catholics call Mary the Mediatrix because she can mediate, or pray to God, on our behalf. If I would ask you to pray for me, you would be mediating for me. But all of our mediation, including Mary's, is subordinate to Christ. Christ is the reason. He allows us to participate in his mediation, just like he allows us to share in his sufferings (Col. 1:24), to further the work of his redemption.
1 Timothy 2:5-6 For there is one God and one mediator between God and men, the man Christ Jesus, who gave himself as a ransom for all men—the testimony given in its proper time.