Toddler speech delay

Aluna

I’m mother of 17 month old girl. My daughter’s doctor believes she has speech/communication delays. My daughter can say

Mamma, Dadda, Hi, and No. She doesn’t combine these words together in sentence. For example; Mamma No or

Dadda Hi. Is my daughter’s speech truly delayed? What’s the normal amount of words for 17 month olds?