Duuude, not to minimize your concerns, but, as the Chinese say, "be careful what you wish for"...
I was SO worried about our daughter re langauge -- something I came to regret sooner than later. Once she started chatting, she never shut up! In fact she is talking (to herself?) right now.
I won't get into ages, because I despise competitive parenting, but our daughter started speaking in two-word sentences very early. HOWEVER, she suddenly stopped speaking altogether for about a year and a half (not a WORD), except to say a very occasional thing like "spider!"... When she did begin speaking again, it was in polysyllabic words and full paragraphs, and she was damn near ready to join a debate team (much to my relief, amusement, and chagrin). My husband still mocks me for being concerned about her speech, but it wasn't funny at the time...
Apparently this is not as uncommon as I thought. Comprehension is the key to quelling your concerns. If your daughter understands you, then you know she's FINE. She'll talk when she's ready. And "ready" means different things to different kids. I do hate the "timetables" that are currently in vogue with pediatricians and the like, though I know they mean well. Too often, in my opinion, they don't take individual children into account.
Trust me, you will soon laugh / rue the day you worried about this!