21month old not talking meaningful words

Hello, My boy just turned 21months old, he still says words like dada nana baba mama papa Tata and a combination of these words, he sometimes responds to his name, but understands simple instructions like come here, let's go and no. He tries to humm the music of cartoon songs and then sing the same using tata and nana words. He has eye contact with me and communicates well in gestures, he tries to help me by fetching my things like socks when we go out. He also gets jealous if I pick another baby. And tried to show interest in other kids games. He also runs climbs the stairs and eats normally, he weights 11.2kgs and no other issues. Should i worry about any development delay? Or speech delay? Does he need a speech therapist? What can I do to encourage him to talk? Please advise! Thank you in advance!