Hi there and thanks so much for your question! Did you know that strength training can add few inches to your height? Regarding to that specific question I wish I had a clear answer to your question. Unfortunately there are many factors associated to our height.
The rate of growth in females varies from female to female. Some females don't stop growing until they are 14, and for some females it is even older. It really all just depends on a the females hormones and genetics although specific exercises can add you maybe one to three inches
Research and evidence is supporting more and more that generations tend to be taller than the previous ones. In practical terms my Dad is 174 cm and I am 183 cm so normally current generations surpass previous generation but sometimes it is not the case and remember that males tend to grow up to 18 years old
I want to try to help you understand how we are getting taller as a society with this reflection from a Professor in Scientific American
Michael J. Dougherty, assistant director and senior staff biologist at Biological Sciences Curriculum Study in Colorado Springs, Col.
"In fact, over the last 150 years the average height of people in industrialized nations has increased approximately 10 centimeters (about four inches).
Most geneticists believe that the improvement in childhood nutrition has been the most important factor in allowing humans to increase so dramatically in stature". to read more copy and paste the following link
My recommendation is to get as much sleep as possible keep stretching also upside down (not for too long though) since in that position your vertebrae can stretch throughout your spine and increase. Then keep eating healthy and stay away of lifting heave weights, that can influence your final height.
Search for my exercises in youtube!
I hope this helps and you have a wonderful day!
Since you are already 18 there are less chances of increasing height more than 2 or 3 inches. However, with the correct food and exercise you can achieve this and beyond. Sound sleep for atleast 8 hours a day is also very important. Take food items that strengthen your body, stretching and flexibility exercises are good for the purpose.