Belief & Prayer

Mark 11:23-24
For assuredly, I say to you, whoever says to this mountain, ‘Be removed and be cast into the sea,’ and does not doubt in his heart, but believes that those things he says will be done, he will have whatever he says. 24 Therefore I say to you, whatever things you ask when you pray, believe that you receive them, and you will have them.

WARNING!!!
These are my raw frustrated thoughts on prayer after losing a very close friend.

I struggle so much when Jesus says this sort of thing. Is He speaking literally? Is He speaking to people like me? Is this bound to His time and context? Do I truly believe? Do I secretly or unknowingly doubt?
I could try to make this idea fit by suggesting that my prayers are answered, just not in the ways I expect. While this is true at times, Jesus said "those things which you ask," and "whatever things you ask." This sounds pretty specific, not general. Could it be that I am not praying according to God's will? If this is the case, is it true that withering fig trees and throwing mountains in to large bodies of water is really more (noble, merciful, loving, etc...) God's will than healing my friend's cancer? How can the prayers of hundreds or thousands be all in doubt or unbelief? How can I make sense of unanswered prayer in times like these?

In the end, these things I know:
God is Good,
God's plan is Good,
Death is not the end,
God's ways are beyond me,
No matter what mountain I face, God is always with me, revealing Himself to me,
He is my comfort and counsel,
God is Good.

Father, help my unbelief. Amen