It's going to be hard for people to help you with no information of the environment your plant is in.
How far is the light from the top of the plant?
how intense is the light? if it's too intense, your plant will start showing signs of light burn while remaining short. If it isn't intense enough, your plant will start to stretch and all the branches will be floppy and falling in on itself from trying to grow too much to get more light.
What's the pH of your water?
There's a few things that could be keeping it short like that, but like i said, you would have to share loads of detaiils. It would be easier if you made a diary.