"If she doesn't go to Pre-K she may not be ready for kindergarten"?
Sorry, J., but that doesn't sit well with me. I'm sure the speech therapist is very good at what she does, but as someone who has taught preschool for a long time, I can't agree with that statement. I would say a play-based preschool would be a far better choice.
For one, kids don't need academics before K, they need more social interaction, positive experiences with other adults (to know that caring adults besides mom and dad can meet their needs and help them), and with other kids.
I would not look at this as *her* choice... I never gave my son a choice of "if you want to or not".... school is NEVER a choice. That is mom and dad's decision. You don't want to present this as a choice because K is not going to be. Don't set up that precedent.
I'd consider doing either play-based preschool or what you are doing at home, with lots of time for meeting up and playing with friends. Do the therapy at home. (My son did eye therapy when he was 5; after his 1/2 day K class-- I did half day in part because we needed to work on those vision issues and full day would have wiped him out for that.) Be diligent about doing the therapy 5 days or so a week at home. If it were me, I'd introduce letters and numbers through play and counting and art, not PreK worksheets. Make the learning come alive to her instead.
Yes, it would be good for her to learn to move along with the group throughout the day. But that is also organic to each kid. Mine has ADHD-inattentive and needs help with transitions, still, even at 9. Typical kids do pick that up pretty quickly; at 5,6, and 7, there is that developmental focus on assimilating, so your child may *want* to be doing what everyone else is doing simply to not draw attention to herself. If it were me, having the opportunity in this situation, I'd wait.
(For what it's worth, we are homeschooling now, but it was my husband's and my choice after a lot of consideration, feedback from him, myriad discussions with teachers/counselors, and frustration with the school not truly meeting his needs. We did traditional school up until a couple months ago of his 3rd grade year. Sometimes he asks to go back just to see friends and I remind him that it's not a back-and-forth choice. This is our best choice for him for *now* and we will keep listening to him-- and planning those playtimes with friends. Being proactive in that regard can really help.)