What an impressive undertaking! I just joined the forum so am entering this conversation late but I would love to learn more from you.
My kids spoke primarily Mandarin until around age 3 when they attended a Montessori preschool, then English has become dominant. Actually, it was rather terrifying how quickly the English came & the Mandarin went! When I first started homeschooling DD for Kinder and was still unsure, it was just easier to use the wealth of resources available in English including WTM. We have Mandarin as a "subject" and do basic arithmetic in Mandarin as well. However, I would like to do more history & science if I can find good curriculum. I'll definitely take a look at your recommendations. 說給兒童的中國歷史 with the CDs would be perfect. What do you do for science?
We briefly subscribed to Dish Network's Chinese programming but found we didn't have much time for TV as the kids got older. However, I'm always looking for good audio resources (CD & radio podcasts). There used be a excellent daily program I think 閱讀哇哈哈 at http://www.ner.gov.tw/ which read stories with short topics on history & science. Unfortunately it's off air now. I'm still searching for a good replacement if you know any.
In California, we are fortunate to have a large Chinese community. However, I'm not in contact with other Chinese homeschoolers. We do have a playgroup/co-op with other native speakers so the kids can practice & enjoy their heritage in a fun setting. Our emphasis is more on listening, speaking then reading/character recognition and less on writing at the early ages. Because most families & our resources are from Taiwan, we use traditional characters. But we've decided to use pinyin instead of ㄅㄆㄇ since the kids already know phonics.
One thought about it all being "tiring" … I don't do true bilingual education on all subjects as you do and I'm already exhausted. I see you also follow Suzuki method which is very time intensive for the parent. At the beginning of this year, I enrolled my kids in a local WTM based history & science program in English. I will probably also outsource LA in the Fall as well. I know it cuts into Mandarin/family time. But for me personally, it has helped me focus on the aspects I cannot outsource and also maintain some sanity.
It's great to find you here. Keep up your amazing work!