I am Catholic and tend to agree with your thoughts about the birth of Jesus. For crying out loud, I guess I'm an ignoramus of my own faith because I had no idea that virgin meant anything other than no sexual relations. Physical virginity? Does this somehow mean that if a poor girl slips and falls in the barn looking for newborn kittens, falls stradling a board and is injured thus, is no longer a virgin? (happened to my cousin) I am a little upset by this because to me it is almost like making that "physical" thing more than what it ought to be. Guess I need to re-educate my mind on what "virgin" means
Of course there's no moral problem with a girl accidentally rupturing her hymen (and some girls have no hymen), but considering the ritual requirements for anything associated with God in the OT (I mean even sacrifical animals, priestly clothing, furnishings, etc --- anything--- all decribed in detail and called "spotless," "without blemish" and so forth) it would seem unlikely that Mary would have been non-intact in any way.
A fascinating Orthodox book, Mary, the Untrodden Portal, relates a parallelism between Mary and various descriptions of the Ark of the Covenant and the Temple in the OT, since these are prefigurements of her in whom God chose to dwell. (Most of it harmonious from a Catholic point of view, although the author aggravates me by constantly spotlighting differences between O and C theology --- diffrences which I think are matters of emphasis and not of substance) --
Anyhow, the point being that Mary's physical intactness is another outward sign of he inward dedication to One Alone, and her fulfillment of the OT signs of God's in-dwelling, his Ark of the Covenant and his Temple.