Mary was already blessed in Lk 1:28 before consenting to our salvation
perpetual virgin
The Bible never says anyone is a biological child of Mary accept for Jesus Christ!
And the Bible says Her child is holy! And Her child is God!
Is 7:14 God provides a sign, a Virgin shall conceive and bear a son! (Singular, one son)
Ezekiel 44:2 “This gate shall remain shut; it shall not be opened, and no one shall enter by it; for the Lord, the God of Israel, has entered by it; therefore it shall remain shut.”
Song of Solomon 4:12 A garden inclosed is my sister, my spouse; a spring shut up, a fountain sealed.
(Mary had become the dwelling place of the Almighty, like the Ark of the Covenant in the Old Testament. Mary was a vessel consecrated to God alone?)
Matt 1:20 But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is conceived in her is of the Holy Ghost.
(The Bible says only the Holy Ghost conceived in Mary)
Matt 1:21 And she shall bring forth a son, and thou shalt call his name Jesus: for he shall save his people from their sins.
(A son singular) (only Jesus is savior)
Lk 1:28 Hail Mary, full of Grace, the Lord is with thee!
Blessed art thou amongst all women, and blessed is the fruit of thy womb.
(The fruit of Her womb is blessed and holy)
Lk 1:31 And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name Jesus.
(A son, singular)
Lk 1:34 Then said Mary unto the angel, How shall this be, seeing I know not a man?
(This verse imply’s a vow of perpetual virginity, She refuses even the exalted dignity of mother of God and mother of our savior if it means violating Her vow of perpetual virginity)
Lk 1:35 And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
(Her son is God)
Matt 1:25 He knew her not till she had brought forth her firstborn son: and he called his name Jesus.
2 Samuel 6:23 tells us: Therefore Michal the daughter of Saul had no child UNTIL the day of her death.
Are we to assume that Michal had children after she died?
Until only states that they had no relation up to that point, the Bible does not say they had sex ever, before or after that point!
First born does not imply a second born. An only child is still first born!