She does not speak either and is really fussy, screaming a lot

Where I live, a child with in that situation would probably be referred for early childhood intervention (a free service where health visitors come to your home and work with you and your child). I wonder if that's available where you live?

For kids that are slow in speaking (or really any babies), one thing that's common here is to use baby sign language to allow them to communicate before they're speaking. We've found it's really helpful for our daughter to be able to communicate things like "more" and "all done" with hand signals. Still working on "hungry" vs. "thirsty", since currently all that is encompassed by "more." I think it reduces fussiness because she can express her needs better and we can meet them better.