I am 24 years old. I am ready to do exercise and yoga too..
If you have not stopped growing, then you may add some additional height. However, the only real way to tell this is to have x-rays done of your growth plates. If they have closed, then you will not be able to naturally add height.
Stretching and yoga may help the slow shrinking that everyone goes through as the spinal cartilage and discs slowly compress over the years.
There is also the possibility of surgical intervention, but this is extremely expensive and painful. Basically your bones are cut and positioned with frames and rods to be slightly apart, and bone grows in to fill the gap. However, this may only result in an inch or so of gain, and has the possibility of being crippling.
If you get into yoga (like I did) you might find that you start standing up straighter.
I'm about as tall as you and what I realized is that before yoga I actually slouched a bit, might of had to do with not wanting to stand out so much (I grew up in a country where I was taller than most people). Eventually I started standing up taller with better posture - which although it might not change your height too much will make you appear taller.
There are other benefits of yoga specifically for tall people too (edit: if you are tall, still not sure where I got that idea from): If you're like me I had very limited back flexibility and really tight hamstrings - neither of those is true anymore after a few years of yoga.