TTC for about 3 months need help

I'm 24 years old and my fiancé is 26 we've been ttc for 3 months now and my last period was in February 20-24,  I haven't gotten my period in March at all and it's now April and still waiting. Taking two pregancy tests and they were positive. So then I went to the doctors the 1st of April and I had taken a urine test there and it was negative. And a week later I went back to doctors and taken blood test it's also a negative. What could this mean??