Every baby is different and they all start to talk at different times.
If you are worried, though, ask your health visitor to check her out, and get her hearing tested.
Keep on talking to her as that's the best way to encourage her to talk back.
Try not to worry, she's still only little.
I would not worry too much. There are, however, ways in which to encourage speech - try to get her to ask for items rather than just giving them to her in response to her pointing to them. Every time you hand her something, name the item for her. Don't push her though - if she feels pressured, she might clam up.
at 18 months old the average number of words a baby uses is 6. Baring in mind some children rabbit away at that age then there must be many who dont talk.
did she have her hearing test at birth?
Its probably that she just doesnt want to talk yet, she may be concentrate on being mobile or developing in other ways.
You can speak to your health visitor about this and they may offer further advice but Id just say talk to her often, repeat all the time. Talk about anything and everything.
Have you got a rear facing pushchair? These are often recommended as baby gets to see mum when out and can connect to what she is hearing in a better way.
My son was able to speak in sentences at 18 months. My daughter couldn't speak properly until she was around 4 years old. She had speech therapy just before she was 3. She has dyslexia which was diagnosed when she was 5. Late speech can be a symptom of dyslexia but sometimes it's just late speech! Just talk to her as much as you can; try simple nursery rhymes with pictures, simple repitition will encourage her.
Don't worry too much.My nephew never uttered a word until he was over 3, then he never stopped talking, and he's a happy chatty 22year old now! Some kids like to take everything in, it doesn't mean they are stupid or behind.
Is she an only child? My youngest didn't talk comprehensively until he went to school, apparently it was because the one 18months older and the one 3 years older spoke and interpreted for him - so he didn't really need to communicate! I was/am a very hands on mum and chatted to them all, gave them individual attention etc, but it made no difference - he got the hang of it fine when he had to - and hasn't stopped since!