I can understand your concern as a mother.Be patient with her.I feel,donot stress too much on this issue for now as she is only 2years and 6months.I am sure she may start in few months.
Next Steps
wait for few months.If she is speaking other words I don't think you need a speech therapist.
Health Tips
You could show her some pictures with you and her or her grandparents and her..ask her who all are in pictures.. Appreciate immediately when she recognises.. encourage her.
you could also play with her in such a way where she has to call you.
Donot stress..be calm