I suppose to be 12 weeks pregnant I been bledding and I was with pain and feeling contractions and…

I suppose to be 12 weeks pregnant I been bledding and I was with pain and feeling contractions and doctor tell me something wrong cus the sonogram don't show I'm 12 weeks they said I'm 4 weeks I don't get it .. Is this possible having a miscarriage with out me knowing ? And got pregnant