Congrats on two heartbeats! How exciting!
If you aren't comfortable with him telling people then you need to talk to him about it directly. Asking us is fine, but we aren't the ones spreading the news that makes you worried you will have to untell if (and I hope you never experience loss. Ever).
Talk to your husband. I don't think you are being overly sensitive about it. Some women/couples/people are very careful about when to tell. There is no shame in that. Truthfully though, there is no "safe" time until the baby is in your arms. So its a personal decision about when you feel comfortable. Were you going to wait another two weeks?