I wouldn't worry. My DD was the same at that age. It was at about 26/27 months and her speech just exploded. She's now 2.5 and we cannot shut her up!
I was also advised that children learn to speak at such varying rates but by three they should be at roughly the same point. Before then, if they show signs they understand, their lack of speech before 3 isn't an issue.
One thing we did do just prior to DDs speech explosion, we thought perhaps she didn't have the muscle definition in her mouth to speak, so a friend advised us her daughter who was speech delayed was offered chewy lollies to help build her muscles. So we gave DD 1-2 starburst chewy lollies a day and it wasn't long after she started talking more. It could have been purely a coincidence, but I guess we will never know.