Lillian, your posts are so reassuring and inspiring. Wise wise words, mama.
Mamafish, my son (5 3/4) is an introvert (as am I). He has a VERY short list of children he prefers to play with (as in 3 kids): One older (a girl, 9), one younger (a boy 4) and one his own age, a girl whom he's played with since he was a babe and whose mom I'm very close with. He is not comfortable in big groups nor with kids he doesn't know well. VERY occasionally, he'll have a rare day at the park and hook up with a kid and play easily. It's usually a girl, usually older. (And she usually thinks she's playing with another girl because DS has very long hair and soft features, but this is besides the point).
For the most part, I try not to sweat this. DS plays independently and we also play together quite a lot and have tons of good family time--all things that nurture attachment and ultimately, maturity.
I'm not sure what your playdate scenario is like. One thing I found early on was that playdates where both of the children's parents are present are very VERY difficult. Lots of tears, anger and frustrations. I started then offering to babysit for a good friend and fellow homeschooler once per week. What a difference it makes to have one parents, focused on both kids. HUGE. I've been doing this going on 3 years now. It's a mutual help to us both. DS has a regular playdate on which to count, and my friend gets some alone time with her DS#2, a few years younger. Because I'm the only parent present, I can focus on the kids, play with them, occasionally provide an activity like baking, tea party, playdough or hide-n-seek, etc., and when they are playing nicely together without me, I can be a fly on the wall and just enjoy the good feeling it is to watch them play. Interestingly, depsite the fact that they gone from 3 to almost 6 years old, they still count on me to be in on the play about as much as when they were younger. I never underestimate just how much a parent can be helpful in child/child relations. I'm especially helpful when I let them take charge and be on the same team together... hide-n-seek is a good one for this and also playing the silly dolt and have them correct me and such. Just get in there and be WITH them, play WITH them, let them take the lead.
Other than that, the older girl, a neighbor comes over a few times per week and DS LOVES her. Maybe a little too much. I've actually had to make sure her visits aren't so frequent that they interfere with our family life (a fellow unschooler which has been very nice but at times, we're a little too convenient, but that's for another thread I need to start
). DS sees his younger buddy once or twice a month--we trade babysitting with his parents who are friends of ours to get some time out together as couples. Despite their age gap, they share similar interests and DS is good with younger kids so it works well.
Moreover? Truly, a little can go a long, long way. And while DS has expressed interest in "friends" I don't think he necessarily means that he needs a ton of them in fact, he's happy with a close few it seems. He's rarely "pining away" for playtime with other kids although he has briefly at times about the neighbor girl with whom I'm certain he has a large crush.
Mostly he plays well at home, explores freely and follows his impulses beautifully. If he were unhappy, I'd have to address that, be more proactive I suppose, but when I look at the whole of the situation, all is good.
And never NEVER, underestimate the power (or good time to be had) in spending time with an imaginary friend.
From one introvert to another... You're doing fine, mama!