My Korean-born son was adopted at 6 months. His speech was delayed, but we unfortunately had testing done at the wrong time of year. He had a chronic adenoid infection that kept him sick all winter long, but would back off in the warm months (when we had him tested). We finally found he had a moderate hearing loss 6 months out of the year due to fluid in his ears, and were able to kick the infection at last with a whole month of strong antibiotic. It was his last chance too, we were getting ready to do surgery the next time he got sick. Thank goodness for Augmentin! We were worried about intelligence too, but he is one smart little boy! We also did some baby signs with him, my favorites were the ones he made up himself.
Our daughter was adopted at 23.5 months, and from what I understand she was only saying a couple of single words in Chinese when we got her. Quiet was encouraged at her SWI. By the time we got home, she had picked up about 10 words in English, and then STOPPED making progress for a very long time. Our state's early intervention program would not help..."what do you expect, she's Chinese!" We were encouraged that she quickly began to understand US, but it was probably two years before she got up to the very low end of "normal" in expressive speech (which I questioned...it still didn't sound very normal to me). She still wasn't communicating easily when she started Kindergarten, but she soaked everything in. I'd say it was 4 years before she could speak with ease. And that was without any professional intervention. So get help if you can, but also realize it can take a child quite a bit of time, especially if they were adopted right around the time they would have started to become verbal. I worried a LOT, but like another poster said, now I can't get her to stop talking!
And she is doing very well in school in spite of some struggles through the 1st grade.