Ever pray for something for so long you give up because you didn't get it in your timing? Yeah, dont do that here. Expect to receive.
But he must ask in faith, without doubting, because he who doubts is like a wave of the sea, blown and tossed by the wind.
James 1:6
Out of the abundance of the heart the mouth speaks. A doubt in your head is ok but never speak doubt. Keep the faith!