These books may be helpful in stimulating your thinking (and your questions) about the Creed.  All are all reasonably brief (some fewer than 100 pages), except for Bird (longer but still very readable) and Torrance (thorough and a bit more challenging).

Bird, Michael F., What Christians Ought to Believe:  An Introduction to Christian Doctrine through The Apostles’ Creed (Grand Rapids, Michigan:  Zondervan, 2016).
A recent and very readable discussion of the Creed.  Bird helps the reader to think about challenges to orthodoxy today as well as in the ancient church.  He includes a bibliography of several books for each chapter about phrases in the Creed.

Gonzalez, Justo L., The Apostles’ Creed for Today (Louisville, Kentucky:  Westminster John Knox Press, 2007).
Helpful about the history of the Apostles’ Creed, such as the “Rule of Faith.”  Some of his opinions are debatable, such as the suggestion that we should recite the Creed even when we don’t actually believe what we are saying, as an expression of solidarity with the rest of the church.

McGrath, Alistair, “I Believe” – Exploring the Apostles’ Creed (Downers Grove, Illinois:  IVP Books, 1997).
This book is helpful for individual reading, but it is specifically designed for small group discussions.  McGrath includes “For Further Reading” and “Questions for Group Discussion” after his treatment of each section of the Creed.

Packer, J. I., Affirming the Apostles’ Creed (Wheaton, Illinois:  Crossway Books, 2008).
It’s by J. I Packer – what else needs to be said?  He is insistent on the importance of the Creed for both catechesis (aka, Christian education) and for evangelism.

Torrance, Thomas F., The Trinitarian Faith:  Evangelical Theology of the Ancient Catholic Church (London:  T&T Clark Cornerstones, 2016).
This book describes the development of the Nicene Creed, and many of the controversies that prompted its careful wording.  Not a light read, but very stimulating and thought-provoking.  Torrance will challenge you with questions you never thought of.  Those questions were helpful in seeing the progression from the Apostles’ Creed to the more robust expressions from Nicea.

von Balthasar, Hans Urs, Credo:  Meditations on the Apostles’ Creed, trans. David Kipp, (San Francisco:  Ignatius Press, 1989).
Brief but helpful comments on the Creed, phrase by phrase, drawing out the theology into worship-enhancing meditations.  In a few places in the book his Roman Catholic views on Mary, praying to saints, etc. will be problematic for Protestants.  His other insights into the Creed make the reading worthwhile in spite of points of disagreement.