Okay, first ((hugs)) it is really going to be okay, really. He is the same little boy you love, those diagnosis's don't change who he is, they are just meant to help you try to meet his needs to help him better learn and grow. His diet is actually really good for an 18 month old with developmental delays, my daughter ate very little solid food until age 2 but is still an excellent eater at age 5 just to give you an idea of how much things can change in a few years. The sippy cup thing is totally not your fault and honestly not something I would worry about at all right now except giving him opportunities maybe once a day to explore a regular cup or try a straw cup if that is better from a dental and oral input standpoint. Some of those things, like stacking rings and stuff, if he's not into it what why not work with him on something he is into and build from there? What does he like, can you sit with him and do that and then maybe help encourage him to expand on that play? Along that line, Have you ever heard of floor time or Stanly Greenspan or this book http://www.amazon.com/Child-Special-Need...028&sr=1-1 ?

I actually think Genetic testing is a good idea for any child who has developmental delays. We found ours helpful and informative. Might be something to do once you get insurance if you are comfortable with it. It's just a blood test.

Also sorry if this sounds too wacky to you but with you having Celiac disease he would probably be a really good candidate for the GAPS diet and it would likely be very helpful to you too. http://gapsdiet.com/ We were gluten and casein free for years and that helped a lot and then we started changing to GAPS which is still gluten free (grain free actually) but has some casein in the form of cultured dairy and that was really helpful for my daughter.