hi L.! my (also left handed) son is just turning 4 in november and he looks like he's over 5 - so I can relate in that aspect about people thinking from just looks he should act older!! (oh how i hate that look).
i get alot of comments (ironically, mostly from people who do not have pre-school aged children) about how i should send him to pre-school this year. Why? Well, "because he's 4 and he needs to do what the other kids do." And I don't subscribe to that belief at all.
Currently he's at a home daycare setting where he's learning pre-school curriculum. He's not at a desk or in a "classroom setting" - but what he is getting is more personalized time with his provider, who is teaching him how to listen, sit still, not talk during "lessons" etc - which I also appreciate because it's not being done in front of a large class of kids so hopefully, *he* doesn't feel like he's just not "getting it" or feel out of place. Some people might call it being too overprotective but I disagree, I think he's doing better there than he would at a school setting - and we know our kids the best.
You will have alot of people on here (and everywhere)that are pro-pre school (no matter what) right at 4 simply because the child is 4 - and in my belief, not all kids are the same. So you base it on what they are ready for on their schedule...not just their age. From what you describe, maybe something like a home daycare that does have pre-school curriculum built in would be a good idea and then next year you could try the pre-school again?
What we've decided, is that at this time is to do what I suggest above - we actually are going to keep him where he is at probably until the school year that he turns 5 - which is next year, and then probably around August we'll determine if we want to send him to a pre-school since he'll be starting kindergarten the year after.
I'll bet you though, that I keep him where he's at - because really, he's thriving there - he gets the play/learning balance - and he's happy. When he does go to Kindergarten he'll likely be the oldest in his class kind of by default because I think the cut off is beginning of September in my district.
Don't know if that helps much, but feel free to PM me if you have any questions on what I wrote.
Best of luck.