Miriam ben Joachim, espoused by Joseph the Righteous, was a virgin before, during and after the birth of Jesus of Nazareth. Her image is to be found in Rev. 12:1.
If you're going to cite Rev 12:1 as being Mary then you have to include Rev 12:2 as well which would undercut Rome's claim on the Immaculate Conception.
1A great sign appeared in heaven: a woman clothed with the sun, and the moon under her feet, and on her head a crown of twelve stars; 2and she was with child; and she cried out, being in labor and in pain to give birth. Rev 12:1-2 NASB
You're also having to ignore a number of other texts that indicate Mary and Joseph did have other children on their own.
A virgin conceived and bore a son.
After that, her virginity was of no import.
The prophecy had been filled and there was no need for her to remain a virgin after Jesus was born.
She and Joseph were free to do as they pleased, since the angel told Joseph to not fear to take Mary AS HIS WIFE.
That comes with responsibilities and privileges.
That’s also way Scripture says Joseph waited until after Jesus was born to have sex with Mary and lists the other children they had together.