Hair can stop growing or grow slower for different reasons (genetics, age , stress or hormones ). Maybe your hair is just breaking , and it makes you think it is not growing. Sometimes your hair can break at the same rate that it’s growing as a result you are not retaining length. ( that’s very common ).
Make sure to be gentle with your hair, don't brush or comb your hair when it's dry, and moisturize your hair more often especially the end .
Also, try to have a hair regimen that fits your lifestyle.