Hi
I have twins...ask anyone with twins about development and the majority will say that each child reached their 'milestones' at completely different times. One of mine started walking at 1 year, the other still isn't (5 steps max) at 21 months!!! The non-walking one is deaf but we have known this from 9 weeks and, although it does affect their development it shouldn't stop them reaching the same goals, obviously.
It is so unlikely that there is a problem, I know lots of people whose children spoke 'late' (who decides these time scales anyway?!?), BUT it is so worth staying on top of things so that if there is then at least you are ahead of the game. Hearing test is an obvious one or, in time, some kind of speech therapy - waiting lists can be forever so we paid to go to a fantastic place in London called Christopher Place. But you won't need that yet...just keep speech therapy up your sleeve if necessary. The worst thing is to ignore any problem which is obviously not the case with you.
My daughter said 'bye bye' today (first words ever!!) thanks to all the help she has had; only 21 months and profoundly deaf. Amazing help out there if you need it.
As others have said before, just keep talking to your child, repeating sounds, always reacting to any sound she makes so that she realises it is worth the effort, and give her the time to talk before rushing in and interpreting her needs for her.
Good luck and keep us posted.