Does hair extensions effect your natural hair growth?

I have hair extensions cause my hair doesn’t grow, or grows very very very very slow. I have the same hair length ever since like the 5th grade. And right now am like in the 7th. But i don’t hair extensions i feel like am losing hair but at the same time i need them cause i have short hair. My hair extensions are 18 inches. And my hair is like a little bit below my shoulders. And i need to know how to grow my hair little bit more faster cause am kinda getting tired of having extensions and i only had them twice.