I am impressed. You are quite a forward thinking young lady. You definitely do not need to give up marriage in order to be a missionary. In fact, as a single woman you would not be able to get into many countries.
The important thing is to find a man who shares your values and ambitions. There are many great Christian men who also have a heart for missions. I would recommend that you skip the P.A. idea.
If what you really want to do is be a missionary, you don't need the intermediary step. There are many people and churches who support missionaries. What there is a shortage of is people like you, who want to go.
See What Mission Work Is All About
I assume that you have had some exposure to missionary activity, perhaps on a short term mission. If not, I recommend that you go on one to make sure that you like it. Even better, arrange to spend a summer vacation working with a missionary family somewhere. See what it is really about.
I don't know which part of the country you are from but most major cities have a least a couple of large, evangelical churches. Contact a church and ask to talk to whoever is in charge of global missions. There is likely an entire section of the church devoted to missions, complete with work groups and activities.
You'll Need An Education
Get involved. Find out what the major mission organizations require educationally. Chances are you will need at least a bachelor's degree as well as some time at a Bible college in order for a mission organization to support you. You will also likely need to be at least 18 before they will place you anywhere long term.
You'll Meet the Right Man While You Work
As to your original question, follow your dreams and do what is important to you. It will be while you are participating in the activities that you value and enjoy that you will meet your future husband. Getting him to "agree" will not be an issue. A man who is also interested in mission work will likely share your values as well.
As you said, you are still quite young and you have plenty of time to decide who you will marry and what you will do with the rest of your life. Mission work is an admirable profession but it is not for everybody. Explore it. If this is really what you want to do, don't wait. The world needs people like you.