Have I let my son down?

I see so many others say their 23-24 months old can identify colors and letters and animals, and my son can do it to an extent, but he doesn’t speak. He says “hi”, “bye” and “baba” (pacifier) but that’s it.

We read to him all the time and we try to encourage him with new toys and books that encourage identification but I feel like he doesn’t know what he should know at his age. 😞 I just wish he would speak. I wish I could communicate better with him. I feel like a terrible mother. He sees a doctor next month.