Could I be pregnant still?

Acacia
Hi, I just had a baby five months ago. On the days of April 3,4 I had unprotected sex. I still got my period April 12-17 . I wasn't feeling good, I went to the hospital on May 3rd, pregnancy test came back negative. So there's no way I could be pregnant? Could the test be to early? Should I wait and see for this months period?