Everyone is different so i think it all depends on how you personally feel. Like you I told my boss and 2 close colleagues. This week is my second back after miscarrying a few days after Christmas, (although told before at the scan that our baby had no heartbeat). I found having these 3 people knowing really reassuring. Not having to hide things and think up lies to them has been one less thing to worry about.
I work in a larger organisation, but there are only about 12 of us on my floor, but i still didn't want everyone knowing - they didn?t know i was pregnant so didn't want them knowing about my loss. I agree it is odd that we ask the question 'who should i tell' as if you'd had a bereavement in the family you wouldn't question people knowing. For me though i didn't want people discussing it and don't want people knowing i am trying. I also didn't want to feel that uncomfortable atmosphere of people knowing, but not knowing what to say. Not because of them, but because it would bother me.
I generally managed questions like with a brief as possible answer that politely answer but infers I don?t want to talk about it. A bug had gone around my office so most people assumed I had had that, but if they asked I didn?t lie, I just said no. Noone has directly asked me why I was off, but if they did I?d either just say I wasn?t well, or that it was non of their business. I have a sneaking that a couple of people have worked it out for themselves anyway.
If you don?t tell people, there is always the chance that someone who isn't in the know, might say something wrong though. On my first day back, after asking me if I?d been off with a bug, a colleague then proclaimed 'we had you down for being pregnant'! ...No, sadly not! This was then followed by another announcing to me that she was indeed 14 weeks gone!! But as hard as those moments were, I?d prefer that than people not being themselves around me.
But I agree with Sam100, make the decision for you, not everybody else. You have enough to deal with.