Firstly, let's make it clear: Nobodoy can force anyone into a marriage.
Here are my suggestions:
1) Just wait for one more year. Until that time, tell him not to accept that marriage. His family has to look after him until his 18.
If they refuse to look after him, tell him to sue his family. Because, as i said before it is their obligation.
2) Both of you: Try to save money for him to go abroad.Then, when he is able to get passport, money won't be a problem for you.
3) Sorry, but he has to perform his military service obligation. It doesn't make any changes if he is abroad or not. Otherwise, he can be denaturalizationed. But don't worry, that obligation starts at the age of twenty, until that time, your problems will be soluted (I hope ).
And..
4) Click on "YANITLA" button to response
(We are sorry for that but be sure we will translate them into English in a short while. )
Hope everything will be OK!