I'm no expert, but it sounds like she's feeling a lot of pressure. I wouldn't ask her to talk, as that's clearly not working. Perhaps instead ask things like "do you want the red one or the green one?", without having them available for her to point at or grab, for instance while they are still in the cupboard (her cups or plates or socks or whatever). No pressure, just ask her, and give her what she indicates. Also, don't let her pull you around by the finger to show you what she wants, if she does that. Have her tell you, but again without pressuring her.
My son was speech delayed, though he was premature. We were new parents and I had probably baby talked him too much, so once the doctor noticed that he wasn't talking at nearly age two and referred us to have him evaluated, and he was at about a 12-month level, we started talking to him like crazy and reading age appropriate books to him, and got him into speech therapy along with physical/occupational therapy, which the activity got him to talk more readily. With less than a year of the "early intervention", he was on track and kicked out of the program (for being on target).
I have a cousin who was the youngest of 7. She didn't talk particularly before about age 5 because everything was done for her by the 8 people she lived with (mom, dad and 6 older siblings) before she even needed to ask, so she didn't "need" to talk. So, wait for her to come to you for her needs, instead of you taking all the initiative.