hi my son is 3years 11 months old .he is using only two word phrases much but not still in sentences.Should i worry?

A. You need to communicate more and more with your child the more you communicate better than speech of child is going to become it is just a matter of time you do like question answers with your child what is your name my name is this this is how you start teaching your child gradually child is going to learn to have better speech and sentence formation over the period