I'm sorry that your decision over whom to tell is conditioned by your fear of getting fired. As if IF wasn't hard enough on its own...
We decided not to tell our families and while my family never asks about us having children, my DH's family does and it's really annoying. We just went to a big family gathering and it was just horrible. Between all the babies, pregnant cousins and annoying aunts I don't know which one was worse... Sometimes I just felt like blurting out, so that no one ever touches the subject again.
I was very open with close friends though, and I don't know if I could have done it without their support. Everyone is always very sensitive about it and I rarely get any questions. They usually just ask how I'm doing and leave it up to me to tell more if I feel like it. There was just one friend I regretted telling to, she had actually also gone through IVF for their first and a couple of unsuccessful FETs for their second child. I thought she understood me, but in the end she just blind-sided me with her spontaneous BFP when she was already 12 weeks pregnant and I felt really betrayed. I wish she would have sent an email or SMS telling me about it so I could deal with it in privacy...
I guess there's just no perfect formula to deal with this.