I don't know what to do or think

I might just be overreacting and overly anxious and emotional. Here is what I'm going through.

I was about a month and a half late and went to my Primary who tested my blood and urine. Both came up negative for pregnancy but since I'm always regular and was TTC she recommended I visit my OBGYN. I scheduled an appointment later at the end of the month but started feeling weird and having some light cramping. I tested on Saturday with a clearblue digital with weeks and it said pregnant 2-3 weeks twice.

When I went to my OBGYN they were off the bat very sure I was pregnant and 12 weeks. My urine sample came up positive and my doctor said she heard a faint quick heartbeat. I was scheduled for an ultrasound the next day since I came up not pregnant at my primary.

During my U/S there was only a formation of a sac and they said I'm most likely less than 4 weeks. The day after my OBGYN calls and says she wants to run a blood test this Friday and another on Tuesday just to make sure.

How worried so I be? Has anyone been in this situation?! I want this pregnancy so bad I can't stop thinking about it.