My advice (reflecting on many years in this journey) is to tell as few people as you can. What may feel right and required now, can take a turn if unfortunately the journey does not resolve in the time you are hoping for. Initially I felt my boss was sympathetic and most friends empathetic (and shocked by what the next steps for us would actually entail.) But fast-forward in time and people in the workplace and whose lives had carried on as usual, didn't have the same patience and "tolerance" for my circumstances, stress and struggles.
I'm no longer in the same job. Legally I could not be fired for my infertility, but my job description and treatment in the workplace suffered to the point of mental duress. Clearly this was the last thing I needed.
What is critical is support. It's important to have people to talk to and help you with the mental and emotional side of your health. Once I knew what IVF was all about, I felt better able to go through the steps and actually found comfort in my business not being everyone else's business. I definitely prefer not to say a word to family anymore. This isn't so hard as we have withdrawn from family by choice as a result of their choices and lack of support through this. In terms of work, in my last IVF attempts (in my newer workplace) I just got my doctor to write me off on medical leave. Since we too commute for cycling and procedures, and the clinic could speak to their distance away and the unpredictability and frequency of my absences, and since my benefits package covers a medical leave, I just said to heck with it and disappeared for awhile. I sent out an email saying not to worry, that I was having minor surgery, some pre- and post- followups, and would look forward to seeing everyone when I was back. I had one friend I would tell. This was the best way I'd ever handled treatment.
I agree with Elizabeth, I hated having no control over the judgments and assumptions others made about my health and family. It's like social media - once you've made a statement, it doesn't belong to you, can become distorted, used against you or later come back to haunt you or your future children. This becomes their privacy and history, too. Then when I'd tell some friends but not others, and if mutual friends and colleagues confronted them, it was really hard to maintain my privacy. I am someone who tries so hard to be a great friend and never speak out of turn when it comes to honouring privacy, so being unexpectedly upset or hearing rumours about me would really catch me off guard. As time passed, I realized everyone else was pretty busy anyway, ironically raising their own families and working... gone were the days of frequent social engagements and knowing what people were doing at all times. Really it just was a work issue. And also, if you don't tell, you don't have to deal with processing how others react, or don't.
My fingers are crossed for you and that you don't have to contemplate this for too much longer