Confirmation is the Sacrament to thoroughly strengthen [con-firmare] our faith and our Baptism. It is done by the Holy Spirit. All that He asks of us is to be receptive and well-disposed.
It sounds like your daughter could definitely use the graces from this Sacrament! So yes, of course she should receive it. (Although of course it is her choice.)
I have to say that Iām not the best person to ask about the whole world religions thing. I was always reading mythology and world religion stuff when I was in fourth grade, and it never seriously threatened my faith. So I suspect itās more pre-teenage questioning that sheās going through, rather than an actual intellectual crisis. But itās also true that she may be getting fed a lot of anti-Christian propaganda by her school, her friends, or the books she reads. A lot of kids are very trusting of anything in print that is new and different, or anything that is said by a peer or teacher.
Catholic Answers has a lot of apologetics material that is very meaty about different religions, the historicity of Christ, etc.
I also suggest that you get her a copy of some early Christian literature that will appeal to her and teach her sound Catholic doctrine. Mike Aquilinaās book on the Fathers is short but very good; Jimmy Akinās book is a little bigger. (DO NOT get anything by Bart Ehrman, as heās anti-Christian and plays some very anti-scholarly rhetorical tricks.)
Get her to read St. Perpetuaās martyrdom diary, in particular. I donāt think thereās a Catholic girl on earth who would be proof against the courage of St. Perpetua and her other martyr friends, told in her own words.
St. Jeromeās letter praising his friend St. Fabiola, whom he didnāt take seriously enough until she made awesome things happen, is another good letter from the ancient world. St. Jeromeās whole circle of learned women friends, like St. Paula, St. Eustochium, et al, are all very interesting to girls. They also teach you what a huge difference Christās teachings made to the ancient world.
If sheās up for it, St. Augustineās Confessions are also something that teenagers tend to enjoy. She might need an abridged version. Itās a portrait of a sinner, and it also shows a lot of why Christians couldnāt just go with the flow of the ancient world.
St. Joan of Arc is another good one. Obviously you have to watch out for material saying she was crazy, a witch, or other stupid stuff; but thereās
a very good Joan of Arc website, and
hereās another with lots of primary material. Mark Twainās bio of Joan is also surprisingly good.
And ask for the intercession of saints like St. Perpetua and St. Felicity, St. Monica, and St. Fabiola, and all the saintly crew. They are good teachers, and theyāve been doing this for a long time!
May St. Joseph, patron of fathers, help and guide you and your daughter!