Back to losing...

i think you played pretty well overall.
The main point I would look at would be how to blunt the power of that g2 Bishop. In general, I like to play an early c6 against a WB fianchetto, develop the b8 N via d7, and consider the d file for the a8 R. This makes it harder for W to develop exactly the threats that proved so effective in this game (d5, b7, c6 all came under the cosh)
I dont know what 15...Nb4 would have achieved, but 15...R(a)d8 would have been worth a go.
As you say, 19...N(e5)d3 would have been good, too!
the big
For starters, the queen bishop is called the problem bishop basically for the problems you had in developing it. There's a fantastic game between Nigel Short and Jan Timman where Timman had a serious problem developing that same bishop, and eventually all of his pieces were "locked" in their positions. Then Short, with all the major pieces still on the board, marched his king right into black's territory. It was stunning to watch that, but part of Timman's problem was finding a good spot for the queen bishop.
Second, I think you're over-commenting. For this forum, it may be ok since it helps to understand the thinking process, but not every move needs to be commented.
Third, you may have to learn how to "appreciate" uncustomary openings in which your opponent chooses to play. Always ask yourself, "what's his/her plan?" after each move because after each move, conditions change.
I thought you had a pretty good outing in this game and was able to take control of this game. I felt comfortable for a moment about your position as the game developed, especially after you played 8...e5. But did you understand what you were doing? I mean, you're advancing in the center whereas white was seeking a flank attack right from the first move. When that happens, you have to restrict his plans from developing. White's light bishop got full control of the a8-h1 diagonal, and also decided the game because of white's use of that diagonal. The queen penetrated the back rank at a8, the bishop got your rook at b7, both on that diagonal. Do not allow your opponents to develop their plans.
I think you're a good player, and things will get better for you in the future, but remember that no one wants to follow your plans, you have to force them to follow your ideas.