We moved to Richardson 5 years ago with a middle school son with lots of learning challenges. As a toddler and younger child he was in Early Childhood and diagnosed with severe expressive and receptive language disorder, sensory intergration disorder, motor skills delay and more. We did very intensive speech and OT therapy when he was younger like you describe. I believe you are coming to a great place for resources. I am not as familiar with the public school resources since our son attends a private school for kids with LD. The Callier Speech Center in Richardson is where I would start for speech therapy questions.
Our son is now getting ready to start his senior year at a college prep private school for kids with LD. He's an honor roll student, sweet and kind as can be, and although he's still a little shy and awkward with his conversation skills, he's a joy and a kid with a bright future. This is a sweet boy who could not even understand or answer a "yes/no" question until age 4 1/2. He didn't talk in more than 2 word sentences until after the age of 6. His language delay was especially severe. He is now in advanced drama and interested in performing in community theatre, and making As in Chemistry too. So, don't get discouraged about your daughter's future. We believed in our son, but he has outperformed our greatest expectations 10-fold from what we saw when he was 5 years old. Speech therapy was a very good thing for him, and finding teachers who were skilled, and would love and encourage him was very important. He attended EC for 2 years, attend a private preschool with speech therapists as teachers for 2 more years, then mainstreamed into a catholic school that was very supportive from 1st - 8th grade while we supplemented with other tutoring and therapies as we could. For high school we chose to go back to a LD private school since we really wanted him to have a college-prep curriculum with small classes and extra attention. I'm sure the public high schools have good resources here too, but in general the high schools are very large which was not what he needed.
Your daughter is younger than school age, but you might want to google for info. from some of the many excellent private LD schools in the area to guide you for ideas on where to start. Shelton and Fairhill are both in Richardson, but people move here from around the country just to bring there kids to these two schools. They are both expensive, and not necessarily the right choice for many kids, but the folks at both those schools are really experts and have a great track record for helping kids reach their potential and stay balanced in the process. It can be a real strain on a family to manage all the emotional and financial challenges with a special needs child. Having a supportive network of teachers, therapists, and other parents was critical for us. You don't have to go the private school route. It can be expensive, although don't rule it out because there is financial assistance available. But, mostly I think it is good to see what is offered for a comparison, and I've found the folks at both schools very willing to help families find other resources that work best for them. Shelton may have some early childhood programs. It is the largest school for LD kids in the world from what I understand.
You are wise to start early and do your homework. Sounds like you are already a good advocate. I've done the ARD and IEP meetings too when we considered public school in Austin, and I found the process quite frustrating too. I just never felt like the benchmarks or expectations were set high enough for our son to ever catch up. That is what prompted us to try the catholic school.
Who knows??? It's hard to know if our son would have grown up almost the same if we'd stayed in public school instead of switching to catholic school. I do believe that what the parents do at home is the most important ingredient, and when it comes time for grade, middle, high school decisions, you will know what works best for your child.
Just don't forget to treasure and love the age and stage your child is at right now. Don't let your worries for her future dampen the funny and loving times you have now. You'll find the help she needs and you need. It's hard to leave an established network of support. I had a very extensive one in Austin that we left. But, I found even greater support here because I became wiser and more confident about advocating for our son as time went by. Age 3-7 was the scariest time for me since I had so many unanswered questions and the emotional rollercoaster was rough caring for a special needs child and two little babies too. I wish I had cried less and spent more time laughing at the park and making mud pies back then. You are on the right track. Hopefully your move here will be a great blessing and adventure for your family. I know our move was.