You read my mind about Mexico! I've been googling marriage in Mexico and came across this interesting fact from the US State Department's 2015 Report on Human Rights in Mexico.
This is from page 21: "Early and Forced Marriage: The legal minimum marriage age is 18. Enforcement, however, was inconsistent across the states, where some civil codes permit a minimum marital age of 14 for girls and 16 for boys with parental consent, and 18 without parental consent. With a judges consent, children can be married at younger ages."
Here is the link to the report:
https://www.state.gov/documents/organization/253239.pdf
JMO.....