Ok, to start with - good decision. Bilingualism is a gift.
Now, I'm a bit confused (not because I was brought up with English as a second language hopefully ), so you might need to clarify for me.
You're speaking English at home.
Father speaks X language.
Country is Y language, not spoken at home.
Is DD's mother tongue English, X or Y? If English, then it is a dominant language. If Y, no problem, she'll be proficient in it once she goes to school.
Anyhow, I don't think the situation is bad - in fact, I think it's great. She will probably be fine in all 3 languages. She will be great in Y because it's spoken all around her; X will be fine because of the nursery; and if you speak English, she'll be fine at that too. She'll most likely be average in each (as in, not worse than average; if she's bright, she may be above average in all three!) and proficient. Otherwise, she might 'drop' one language of her own accord, although that's rare. It might be the case that she drops one as she gets to adulthood.
I can tell you that the dropped language won't be English, though! English takes care of itself, really it does.
Finally, it's a mistake to compare her with monolingual children. Of course they're more articulate...now. She has three languages - and will be articulate in all three! So she'll catch up. Often, bilingual children are slower acquiring language than monolingual ones, but it's nothing to worry about.
I think you have your solution - you're doing everything right. She'll be a good linguist, adaptable, and also quick to learn other things (music, perhaps).
I'm bilingual and very much older! I hardly had any English at home, and some at school, but I learnt it quickly enough - I'm totally bilingual. And I wrote my Oxford PhD thesis in English.