These books are all recommended by Fr. Joseph Welch. Many are available on archive.org.
I’ve put some in bold that you might find especially helpful.
Introductions to Catholicism
A Compendium of Catechetical Instruction by Monsignor John Hagan, 4 volumes (approx. pp 500 each vol), 1928-32. o/p. An outstanding commentary on the Catechism of Pope St Pius X p…