I am not saying that you haven't been called. But I find your discussion of how you have been called to be lacking and it makes me wonder.
Phrases like "I've seen God's provision in working out this opportunity" are Christian buzz words in and of themselves and say nothing. How has God provided? If He has, there is a story. The "little voice" in your head could be wishful thinking or acting out your romantic vision of things. Not for one second am I saying that God does not speak to His people, but a whole lot of people confuse what is in their head with the voice of God.
I used to recruit sdtudents for a Christian college. Often when I would call students would say "God has called me to another college." I always said the same thing: "That's wonderful! And how has He called you?" Most of the time I would get Christian gobbeldygook:"Well, ya know, He jujst sorta led me." "He's given me an inner peace about this." "I just felt the leading of His hand." They were parroting back buzz words they had learned. When someone had been led, they had a story, sometimes some pretty interesting, even bizarre stories, but they could tell me exactly what had happened in their lives to get them to that position. Sadly I think we have taught Christians to spiritulize decisions that are mearly their own decisions.
How well have you researched mission organizations? There is a huge variety of them, of all different sizes and focuses. Is your slamming of "big" missions based upon what you have learned through your own research and study or what this guy from this fledging mission has told you?
And if indeed God is calling you to this mission, is He calling you to go now?
I don't know what God is calling you to do. I'm asking you hard questions becasue you need to be able to answer them, for yourself, for your parents, for this mission organization and for anyone you are going to seek support from. I'm not talking about learning the right things to say.
Have you read some biographies of missionaries? I think you may find them very interesting and helpful reading.