Delayed toddler

My parents are constantly worried about my sons speech, development, potty training etc. I know they are concerned and mean well but it’s very hard for me to potty train him since he doesn’t speak very well yet. He is 2.5 and may be a little behind on speech but the doctor said he isn’t concerned and isn’t going to get us help unless he’s concerned. My mom keeps fighting with me about sending him for an evaluation and speech therapy. Where can I go to get this help? Insurance won’t cover unless there is a diagnosis.