Here is a great solution.
Baptize your child in any of the Eastern Orthodox Christian Churches.
Culturally and aesthetically -- your Armenian heritage should feel some satisfaction.
Legalistically - for your husband's parents -- all Sacraments in the Eastern Orthodox Christian Churches are viewed as valid by the Roman Catholic Church.
Raise your child in the Orthodox Christian Church in America. It is in full communion with all Eastern Orthodox Christian Churches. You can locate parishes at the church's website. Find a newer parish and you are likely to find many people from backgrounds like you and your husband.
Later if the child ever wants to fully commune with either the Armenians or the Roman Catholics -- it should be a very simple affair. But at least you have given him a good foundation from both sides of your family's religious inheritance, culture and holy tradition.
Your Mother-in-law if she is really knowledgeable of Roman Catholic catechism will understand this. If she is less-than-knowledgeable, she might require some education on what the Roman Catholic Church teaches and believes. A good OCA priest should be able to help you negotiate the whole thing especially with the in-laws.
I hope this helps.