Thanks everyone for the encouragement! :-)
The spotting stopping and successful treatment of the bladder infection are both good signs. If the doctor indicated that the ultrasound looked fine, that's encouraging too. I've read many women who had ultrasounds at 6 weeks only seeing a sac and then seeing a baby on the next ultrasound. You need to follow up with your doctor this week for another ultrasound and to check that your bladder infection is improving. That will give you more reassurance that everything is back on track.
Good luck!
I also had spotting around the same time and also at nine weeks. At 6 wks I went to ER with a fear of tubal pregnancy, and same as you they only saw a sack and no heartbeat. It wasn't until week 9 were they able to see a heartbeat. I was put on progesterone pills after some bloodwork was ran and I am now 16 wks with a healthy babe!! Hope all goes well