You said intercession. We are commanded to pray for one another, and we can ask Mary, who is in heaven, to pray for us, just as I can pray for you, or you can pray for me. This is all that is meant by intercession.
You are very right that we are not to pray TO Mary, but we can ask her to pray for us sinners, which is exactly what Catholics do when they pray the Rosary.
“Holy Mary, Mother of God, Pray for us sinners, Now and at the hour of our death, Amen.”
Show me in the Bible, where we can ask people *in* Heaven to pray for us and I will concede the point.
It gets so old, Catholics praying to Mary, Catholics idol worship to Mary, to the Saints. Old old old. As Catholics we DO NOT worship Mary as does any rite in the Catholic church. I love Saint John the Baptist and Jesus had wonderful things to say about him, his moral courage in standing up against the sinfulness of a particular politician even to the point of death was because John was courageous because he was NOT corrupted like so many clergymen today. I wish we had more men like him. Mary is yet another to pray with and to be honored because GOD first honored her. Not everything our Lord did and said was in Holy Scriptures because as it said there would have to have been too too many books to contain all he said and did. We are blessed by the guidance of the Holy Spirit. For those who do not recognize the love of Mary it is the love Christ has for all of us and we are to have for one another especially for someone like Mary, we are to love. The Sacred Liturgy is the example of the worship of our Lord that is best to show our Catholic Faith, with the power of the Holy Spirit. Mary is compared to the Ark of the new Covenant, http://vivechristusrex2000.blogspot.com/2009/06/blessed-mother-ark-of-new-covenant.html
I am also a Catholic convert and I also had a problem with Mary only because so many people told me it was wrong but we all have a personal journey with Christ to follow. I was arrogant, full of myself. If our Lord had favor with Mary then so shall I, she only makes me love him more because she raised him, loved him and grieved him. It’s just not a story in the Bible it’s a real family of our Lord’s, it’s personal,it’s who we belong to, she was the mother of our Lord. How many times should we thank her? For some of us we understand her grieving losing Jesus to a torturous death because we too lost someone we love. I love her not over our Lord but because he loved her. I think it’s hard to understand Divine Love, the way Christ loved because too much of the time Holy Scriptures is used for debating and we forget how much it’s all about the Divine Love of God, teaching us how to love as he did, which can be too difficult for so many of us. So I love Mary just as our Lord did first.