Luke's Story of Jesus' Birth

I was delighted to encounter an article this year (HT: Anthony Le Donne) that suggests the following story line in Luke's birth story. [1]

• Mary becomes pregnant of the Holy Spirit in Nazareth before she and Joseph get married.
• He returns to his family's home in Bethlehem for a census. He takes her with him.
• They get married in Bethlehem--he takes her into his house. 
• Following the normal practice, a small make-shift room, a marital chamber, is added to the family's house, often on the roof as a kind of attic addition. This would perhaps only be big enough for the pregnant Mary and Joseph to sleep in.
• She gives birth in the main room of the house, since there was not room for birth in the "place" (katalyma) of the marital chamber. 
• Many "farm houses" of this sort had a manger, with animals on the lower part of what was effectively a split level (with about a one meter height difference). They lay Jesus in this manager.
• Forty days later, they return to Nazareth.
• Merry Christmas all!

[1] Stephen Carlson's 2010 article from New Testament Studies: "The Accommodations of Joseph and Mary in Bethlehem: katalyma in Luke 2:7."