Hi there Amna. Quite the interesting topic.
Height is determined predominantly by genetics. In order to more accurately determine how tall you will be, you have to observe the height trends in your immediate family going back about 2-3 generations at least. If your parents are on the shorter side, but all 4 of your grandparents are tall and so are your uncles and aunts, it indicates that your parents inherited genes that limited their height development. It is most likely that they will pass on the same trait to you, as they are the only ones within their generation to be affected.
If a majority of your family is short, it is also most likely that you will remain within the same height range. The majority indicates what the dominant trait is.
I won't get into any more genetics... some of that is explained in the link I'm posting.
Excercising does help, but only to a limited extent. Excercising ensures a well-developed cardiovascular system and maintains flexible and limber muscle toning. These aspects definitely help in ensuring proper height development. Drinking milk, as someone mentioned, also helps. Milk is the primary supplement of calcium. Our bones need calcium to develop and maintain their strength. If the bones are deprived of calcium, their development will be affected, which will most likely effect growth in some capacity.
On average, females experience growth spurts till about age 18. At this point your body has regulated the hormones and development to a point of maturity. Some women can experience a growth spurt even after 18, but that is rare in today's society. Males have till about age 22 as their hormonal development and regulation takes a bit longer.
Here's a link with more information regarding height and genetics. Skim through as it gives a lot of good information that you may be interested in.
Wikipedia - Height and Genetics
As for me personally... I'm shorter than my parents, and at times I, myself would like 😆 However, "shortness" seems to be the predisposed trait for my generation. With the exception of one male, the rest of us in my generation are in the lower 5' range. All of us, incidently, have at least one parent who is of above average height (ie: greater than 5'4-6"). Our grandparents, esp the males, were typically above average height as well. I'm assuming the gene for lesser height was passed on, esp through the females, and is affecting my generation.
Ah well..good things come in small packages 😉
Hope this helped and wasn't too much science. I never realized just how much I'd learned 😆