just to encourage you, my niece also stopped speaking at that age, after she had 3 words or so, and she continued to be speech delayed. She was evaluated at 2 1/2 and received early intervention that made all the difference. It's only a year later and her speech and communication have passed up my son who was not speech delayed, but he has autism. She does not appear to have autism at all, but was simply speech delayed. Her mom has dyslexia, so they are watching for signs of that as she enters school. Just wanted to encourage you, but also to make sure she does get evaluated as soon as possible because that early intervention is so critical, no matter what her diagnosis turns out to be.

even if he can't yet be be formally assessed for all developmental skills/progress, which I am sure some places will...You could also take him to a speech-language pathologist had have his language/speech assessed, children as young as 12 months can qualify for speech/language therapy, and at least they can answer some questions and give you some ideas

At 18 months my DS spoke, a lot. By 20 months he has lost 3/4 of his vocabulary. He was diagnosed with classic autism by 23 months. It's called autistic regression. Now at 3 he is considered moderate to severe autism. Good luck on your journey.

as far as it getting harder ha my kid has ran blocks around the most energetic people i ever met he doing better in the last 9mmonth but we know what to expect already how ever the emotional stage of things for me n the communication or lack there of from him to me or people at all yes it takes alot not to kinda b hurt for him hect it breaks my heart that my son prob has so many things he wishes he could just say but i myself am not one to cry over many things i decided over year ago no tears will help isiah onlyway was to keep seeking as much knowledge as possible about autism ,I have him in school thru early intervention program Willamette ESD he is ok more now then ever I personally work hard every day with him on speech n his listening as well as behavior management he often will wind down with a simple change of rooms, lighting & book that he enjoys. we call it his quiet chair time

Was just thinking, make sure they don't put you off in evaluating him, it can be such a lengthy process. When we first started checking into it, we only had some mild concerns, by the time we were finally done, we were getting desperate for help, his behavior regressed that quickly. They just change SO fast at this young age. So as soon as they will allow it, 18 months? I'd get started. It takes some emotional energy out of you, be prepared. Just take it one day at a time.