In Romeo and Juliet, is Juliet too young to marry?

Shakespeare himself must have felt that
thirteen was pretty young for a girl to get married. Otherwise, he would not have spent so much
space seemingly apologizing for 's tender age. She herself says she feels to young to think
about getting married to . Juliet's mother seems to think it is okay for her daughter to get
married, especially since Paris is such a good catch. Juliet's zany nurse assures Juliet that it
will be just fine for her to get married at thirteen. Juliet's father tells Paris that he thinks
his daughter is too young. Paris argues that lots of girls Juliet's age are already married and
have even become mothers. This sounds like Shakespeare's argument and justification. He must
have had some reason for making Juliet thirteen when he could have made her fifteen or sixteen
with just the stroke of a quill. I suspect it had something to do with the boy-actor who was
going to play Juliet. He may have been only twelve or thirteen himself. If it was so common for
thirteen-year-old girls to get married in older times, then why did Shakespeare make such a big
issue of it? Why did he even specify Juliet's age at all?