I know it sucks, but it's soooo common. With this pregnancy I sat in the ob's office at 5 weeks crying my eyes out because I had spotting that morning and I was sure it was over. I had him convinced too. He hugged me and everything. I'm now 29w and she's rolling around as I type this.
Seeing the hb is a huge step. I honestly believe everything is fine for you. Hugs.