I actually wouldn't worry too much about it. If she's going to grow up in the US, English WILL be her main language. She will hear it on TV, from friends, all through her schooling years, she will read English, she'll have no choice but to speak it. And as SHE learns to speak it, YOU will also improve. The challenge for you, as she gets older, will be to keep her fluent in Sinhalese, too. At some point, she will probably be the only one of her friends that speaks it and might refuse (she wants to be like her friends and not stand out). I've got so many friends who are raising bilingual kids and right at the time peer pressure starts, they revert to only English for a while. Then it becomes "cool" to speak another language and they start up with their second language again. If I were you, I'd actually keep speaking only Sinhalese to her, but set up lots of playdates with English speaking friends, enroll her in English speaking pre-school (like there's much choice there in the US), let her watch TV in English, read her books in English. There are many families in the US where parents speak NO English, but the children are perfectly fluent in both, speaking English like an American and their native tongue like a native. So your daughter will be just fine.