Why aren't the dwarves in possession of their treasure? How does this make them feel?

The dwarves are not in possession of their treasure because it was stolen from them. After it was stolen, they wept and cursed Smaug for taking it from them, and although they've gotten over it....they still mean to have it back.

"The few of us that were well outside sat and wept in hiding, and cursed Smaug; and there we were unexpectedly joined by my father and my grandfather with singed beards. They looked very grim but they said very little. When I asked how they had got away, they told me to hold my tongue, and said that one day in the proper time I should know. After that we went away, and we have had to earn our livings as best we could up and down the lands, often enough sinking as low as blacksmith-work or even coalmining. But we have never forgotten our stolen treasure. And even now, when I will allow we have a good bit laid by and are not so badly off"-here Thorin stroked the gold chain round his neck-"we still mean to get it back, and to bring our curses home to Smaug-if we can.

No