Hello everyone I am a roman catholic thinking about orthodoxy a lot

. I recently read some of the early councils and the filiquoe is not in it. This is what sparked my interest in orthodoxy .
I have read St basil on the holy spirit and st Athanasius on the incarnation and now am reading St. Cyril of jerusalem on the unity of christ. I have also read the apostolic fathers
what are some other good books to read about orthodoxy ?and what is a good book to explain the holy theotokos.

?
thanks for any response to my questions