How to increase my height?

Change your parents.
Or if you can’t do that, wait it out. At 14 you should continue to grow.

I am 6’5”. I ate more meat and veggies as I grew. Eggs and toast for breakfast. sandwich and cantaloupe half for lunch. Beef stew for supper. Tin of smoked oysters with bread for night time snack.

Stand back! You are about to hit a growth spurt! I grew like the dickens between the ages of 14 and 16.

Your height is not in your control. I would think instead about your personal carriage.

I took a few years of martial arts (Krav Maga). I am not any kind of fearsome fighter, but it gave me a lot of confidence and I stand up straighter, and look people in the eye and engage them instead of being shy.

Like @kritiper I was also quite short when I was 14 but I grew quite a bit over the next two years.

When I was 14 I was 160 cm. When I was 15.5 I was 186 cm. It happens. Don’t get to discouraged and just enjoy life.

Oh! And Welcome to Fluther!

Eat right. Exercise. Be active. And don’t smoke!
Let nature take its course.

I went to school with a guy that was 5’2” until he was 17. He then had a growth spurt and ended at 6’4”. I never met his father, but his mom was about 5’4”.
So who knows, it could happen for you, too.