Hello. Welcome. Weight is easy, height, not so much. You've mostly grown your full height by 26 years old. I think there are some well known actors that have insoles in their shoes that increase their height but most likely you at your full height now. Once you've gone through puberty, it's kind of done. There is human growth hormone but that is given to those lacking it in the early teen years (I have two nieces who received this). My nieces were deficient in this and took shots daily for a good while but for them, it was a full health issue and not to just gain height. Are your parents of short stature? Genetics are the biggest predictor of our height. I have two kids and one is quite tall. Always has been in the 90th percentile for height. One is short and always has been. He's always been in the 30th percentile for height. It was like this when they were one year old and continues until today. It was set up from the beginning in the genetic make up. So, sometimes coming to terms with this is important. I know it is not easy for a man to be dissatisfied with their height. I'm sorry about that. Staying really fit helps the men I know like this feel better about it.
Weight lift, work out, add extra protein and carbs to your diet. Gain weight the healthy way and not by eating junk.
Let us know how else we can help you.
I've heard of leg-lengthening surgery but have no personal experience with it
... you may find further information on it on the internet if you care to google it.