As everyone else says it's entirely personal.
I'm a fairly private person but pregnancy does seem to make you public property, people are quite happy to discuss you/your body as if it doesn't have any effect on you.
There is no reason to believe you will mc, even if you tell the whole world.
My experience I didn't tell anyone except DH with my first pregnancy, and I mc at about 8 weeks. The second pregnancy we told people at 9 weeks because we were getting married when I was 12 weeks, so it would have been obvious and also I realised I would have needed the support if it had all gone wrong again. I went on to have a healthy DS.
Next time we told everyone (family etc.) again at about 9 weeks and I had a mmc at 13 weeks. This time we didn't want to tell anyone until approx 16 weeks, but my nosey MIL kept asking and my DH doesn't like to lie so he told her (I was furious, at her ... not him, but completely over that emotion now). I am currently 30+ weeks.
So I have experience both ways and it doesn't make a jot of difference. It is such fantastic news to share, it's hard sometimes but try to enjoy it as much as you can.
Congratulations by the way.