Miscarriage not bleeding

Please help me to understand what is happening. I was 4 weeks 6 days pregnant yesterday, I hadn't been feeling right since I found out I was pregnant as I had no signs. So I retested and on a FR there was only a really faint line and a digital said not pregnant (I hadn't done a digital previously though just a normal test and a FR which both came up with strong lines last Sunday). I went to the doctors and she tested my urine using their test and she confirmed it was negative and said I should start bleeding. I still haven't started bleeding and I am feeling nauseous. What is going on?! Can you have a miscarriage so early and just not bleed and it be like skipping a period? I'm so confused!