Flying in the first two triemsters is perfectly safe and the only reason they don't like you to travel in your third is incase you go in labour, but in saying all of that, being sick on a plane is the worst! I travelled to the UK when I was 14 weeks pg with DD and still suffering from m/s... It was just horrible and I am so put off going back to KL air port just because it is a complete reminder of how terrible I was
Your boss has an obligation to you to keep the information confidential until you make it common knowledge. The only reason he may have to tell someone is if another boss or somebody in a high position needs to know why you are no longer travelling. Just make sure you do say that you will not be telling anyone else for several weeks to come yet. I had to do the same with my boss as my job does involve some heavy lifting, when I give her the A OK then she knows I'm telling people.

Congrats on your preg, I wish you a very H&H 9 months. I hope you don't get too sick.