I am a speech-language pathologist and have been working in the school setting for 6 years now. While most children in monolingual homes do have larger vocabularies and are putting together at least 2 word sentences by 2, it isn't atypical for children from bilingual and multi-lingual homes to have language that progresses at what seems to be a slower rate. When you think about it she's learning each word and how to structure a sentence in 3 languages. So if she has 40 words in each language, your daughter has actually acquired 120 words. Additionally, sentence structure varies from language to language which can cause a slow down as well.
I would suggest keeping an eye on her language development. Your concern shows that you are monitoring her development well. Do keep track of what words she currently knows in each language, as well as her 2 word utterances. You can have her assessed through Regional Center under 3 years of age. Once she is 3 you can have her assessed through your local school district free of charge.
In the mean time - like I said, keep track (it sounds like you already are, but it will help if she is assessed to have good records of this). Also, instead of asking her to repeat words and phrases after you, involve her in language rich play. Use baby dolls, other toys and just talk alot. If she says something like "dolly", for example, you can expand that for her, "Your dolly is eating" or "The dolly is sleeping." Nine times out of 10, children will begin to repeat words and phrases they hear alot in a more natural setting. Reading and looking at magazines or pictures is also a wonderful way to increase language and vocabulary development and your daughter won't even suspect that's what your doing :) Right now she's young and still learning - play is the best way for her to do that. Just bombard her with language. When she wants something, do make her ask for it with at least one word, like "Milk", then say, "Oh, you want milk? Mommy will get you milk". It might feel weird at first, but it pays off HUGELY.
I hope some of this helps. :)
G.