When to tell work


I work as a nurse and mainly work nights, my manager is asking me every day if I’m pregnant and I just keep lying (I’m 9w 4 days). I’ve had pretty awful sickness and did have to have a day off work due to constant vomiting. I also had some bleeding yesterday and had to have an early scan. I just don’t feel ready to tell them, my manager can’t keep a secret so as soon as he knows EVERYONE will know. I’ve not even told my siblings yet as was waiting for 12 weeks. However it’s starting to become difficult as he’s asking other staff and putting me in a shitty situation really. Can I continue lying until I’m ready?? Is anyone still keeping it from work?