There is a HUGE range of normal. You asked, so I'm going to answer, but I don't think comparison is the right way to go on this. At 12 to 15 months my son had about 35 words and used a few phrases (stop it, more please) but THAT's not normal either! I think his 15 month appointment, they were looking for 3-5 words beyond mama and dada.
Remember that any list of TYPICAL development is about finding a middle point between our children.
If you haven't considered signing with her, now might be a good time to start... one of the reasons we understood my son's speech early on was because he was making the sign WHILE he said the words... I might have thought "Momomomo" was just babble as an infant if he hadn't been signing more more more more while he said it.
A lot of what I'd be watching for as mom is to see if she is making NEW sounds... if she is IMPROVING. If the pediatrician isn't worried, I wouldn't be either. Keep talking to her. If you are concerned go back to the pediatrician.
HTH
T.