I homeschooled my 5 children for years. Our 1st 2 children graduated from homeschooling. We put our remaining 3 children in PS (all for the 1st time) in 2005. Our 1st 2 did attend PS when they were much younger. Our kids transitioned very well to PS & excelled in their classes, made friends, kept up with their schoolwork, and adjusted to a more rigid schedule very well. We had been part of an educational co-op which also helped, they had lots of friends from church, youth groups, AWANA's, and this co-op. I am now schooling my 11yo son again as he was having many issues at school and I am currently in the process of having him evaluated for aspergers syndrome.
Seems to me that most people that say 'what about socialization' have never homeschooled and have no idea how well these children ARE socialized. Yes, there are a few out there that seclude their children from others, but very few and I've seen many PS kids with similar sitauations.
The pro's for us was more individualized attention and a lesson plan that allowed them to master the subject. If they were struggling we could take as long as needed and didn't have to worry about 30 other children that need to move ahead & deadlines of a school year. They were also free to study more in-depth the subjects that interested them for instance my 11yo is fascinated by WWII History, he could study it all day long. MY oldest daughter loved art and never understood why in ps Kindergarten she wasn't allowed to dray as long as she wanted to, LOL. I felt we were able to also teach the values that are family hold firm to and to draw closer together as a family.
Con's..it's not cheap to homeschool ALTHOUGH with some research & hard work it can be done. BUT it's usually far less than a private school education. There are days that are frustrating, kids are grumpy, Mom is grumpy, things they knew yesterday are gone today, but that's true in a ps situation too. If you are one that is active in a weekly morning Bible Study, Sewing Club, volunteering etc. those things get put on hold for these few years that you are shaping your children's education. I never missed those things.
I highly recommend homeschooling to anyone with a child that is struggling or one like your daughter. My oldest, even in K, did not understand all the silly, giggly girls. She had 1 good friend and that was good enough for her. She didn't like how some of the kids were mean and often defended the underdog.
And yes, it's ok to homeschool 1 child and not the other. I have friends that did that very successfully. Some kids personality fits best in a PS environment, some are better in a HS environment. If there comes a time that your 3yo no longer needs the therapy, then you can make a change then if you so desire. But check with your school system first, through the administration not so much her therapist and see if they are required to offer therapy regardless if that child is in classes or not. When we lived in WA my son took speech therapy & he was not enrolled in PS.
And as far as transitioning back to PS, my kids had no problems. When I put them last 3 in I had 1 in elementary, 1 in middle school and 1 in high school. All did really well. My youngest (the 1 that was in elementary) did well in the smaller school in TX than the larger school here in Germantown. But he has other issues going on that have made it so that we felt homeschooling him this year was the better choice.
And one last bit of advice. Let your daughter know that IF you decide to homeschool, you will do it for at least 1 school year, no changing her mind midway through the year. Commit to 1 year at a time because there will be times she will most likely get frustrated and say "I hate this I want to go back to school' or you will be tempted to say 'we should've left you in school if you wont do the work, etc'. Just try & tame the tongue, relax, enjoy the experience. At the end of each school year, sit down with her & your hubby and evaluate how you think it went & where you'd like to go next year.
Hope that helped.