Speech delay

I need some encouragement, my 3 and half years of son is still not talking (communicating) but he can say 1-10 and some alphabet. We did a hearing test and he’s fine. He just started pre-K last October. I am not seeing any improvement. He’s also not potty trained because he can’t talk and communicating with him is the hardest part of my day. What is the longest it took for your child to talk or someone u know. I am very concerned. He has not been diagnosed with anything he’s perfectly healthy.