Possible Miscarriage?

In the month of February I thought I was pregnant I had five tests come back positive not the same brand nor out of the same box. When I finally called the dr they had me do a blood test and it was Negative. I was so confused because I just knew I was pregnant. I've been pregnant before. I have a 6 year old daughter. I asked my Nurse if there was any way it could be wrong or if it could possibly be an early miscarriage as I would have only been a couple weeks along. She said no there was no way. I was still so confused because I've never felt more pregnant other than when I was pregnant before. I also wasn't bleeding or anything but I did start having some really bad lower abdominal pain and I did start bleeding a few days later I bled for about 3-4 days passed a bunch of clots and I haven't started a period since and that was February 13th. I did some research and read that not only do you not always bleed from a Miscarriage but you can have a Silent Miscarriage with absolutely no symptoms at all. I'm still pretty convinced it was a miscarriage. I'm wondering if anyone else has had this happen or what you think happened. Thanks for reading and please no negative input.