RE: How old was the Virgin Mary when she was be-throed to Joseph?
The Bible does not say, so we can only speculate.
In Isiah 7:14, it says : Therefore the Lord himself will give you a sign. Behold, the virgin [Hebrew: ALMAH] shall conceive and bear a son, and shall call his name Immanuel
The Hebrew word ALMAH refers to a young girl that reaches puberty but still under the care of her parents. Mary being an Almah may have been espoused to Joseph as a teen.
Betrothed. I hope she wasn’t bethroed, lol.