positive test but blood test is neg?

I got 4 positive preg test Dec 28 my cycle are always regular every 32 days. When I saw the pregnancy test turn positive I was sooo happy we have been trying to conceive since 3/2016 with no luck. I was so happy that I call my obgyn and made appt right away and I also made appt with my endo (DM type 1) and also I told my husband he was so happy we decided not to tell anyone until 13 weeks on Jan 4 I had some light cramping with dark brown discharge around 1pm I took another preg test and still positive but line was a bit lighter than the other 4 test I had took on dec 28. I called my on dr and he order labs for me to do that day later around 430pm the brown bleeding turn into bright red with cramping again. I went to ER after work because I was preg and vaginal bleeding they did preg level blood test they said you are not preg . Level is too low it is at 3 on should repeat in 1 wk . I was so sad and upset.