Hello I am a sixteen year old girl who is 5 foot 6 inches I want to know if it is possible to gain two-three inches.?

Not likely... If very tall people are in your family, and especially if they grew late into adolescence, I guess it might still happen but otherwise, it's not likely for that much additional growth. Other medical issues may matter too, so talk w/ your doctor about your case. You might gain a bit more and I hope you can feel satisified. Best!
Unlikely. The major driver for height originates in the long bones of the body, primarily the legs. When the growth centers of the legs have quit making new bone, as would be expected by 16-17y in a female, you're as tall as you will ever be. An x-ray if the hand can be used to demonstrate you're bone maturity & if the growth centers show open growth centers you may grow taller.If not you're done.
Yes. Because you are 16 years ,it is possible you grow 2-3 inches.