Baby won’t say anything but dada

Anyone else go through this?? My 1 year old used to say mama, dada, Pap, blue, pink. And now the only word she says is dada. Our ped said if she doesn’t talk more by 15 months she needs speech therapy. I’m so sad I try so hard. But all day every day it’s dada dada dada lol in all seriousness though, should I be concerned?! Tia