Remember that knowing God’s will is really about knowing God. We make a mistake if we think of God’s will as a road map we need to read. It’s not like getting directions from Point A to Point B. Proverbs 3:5-6 calls us to “trust” in the Lord and to “know” him deeply and intimately in all our ways. As we do that, he will lead us from where we are to where he wants us to be.
I would say, if you sense or feel or believe you should to Myanmar on a mission, then by all means set out to go and trust your future into God’s hands. But understand that setting out to do something doesn’t mean it will come to pass exactly as you intend or expect. Things may happen that make the trip impossible. Or if you do go, it may not be as you expected. But none of those things should us. When serving the Lord, let us set our hearts to follow Christ wherever he leads, and let our motto be, “Expect the unexpected.”
Can you “know” it is God’s will about going to Myanmar? It’s depends on what kind of “knowing” you mean. If you want 100% certainty, I doubt you will have that. We rarely get that this side of heaven. But if you mean, “I have prayed and thought about this and discussed this and sought godly counsel, and I believe we should set out to go to Myanmar,” then yes, we can have trust that setting out in that direction is God’s will. Generally we are given enough light for the next step. Just one step. God never guarantees the destination in terms of our earthly plans. So take the next step, and trust God to lead you on from there.