With my first pregnancy with our daughter I was sure I was pregnant. But we were on vacation with my MIL (who is very nosy) and I didn't want to buy a pregnancy test when she was around. I woke up one morning to some spotting and thought for sure my period was starting. I was very sad that I wasn't pregnant. But, the spotting only lasted a day and when we got home I took a pregnancy test that was positive. We have beautiful daughter who just turned 2!
With my 2nd pregnancy, I had no signs at all that I was pregnant. I thought I may have missed a period, but I had just stopped breastfeeding and several friends had told me it had taken them several months to start regular periods again after breastfeeding. I only took a pregancy test because it was New Year's Eve and I wanted to make sure I wasn't pregnant before I had anything to drink. I was completely taken by surprise when it was positive because just a week before I had a negative one right before Christmas. We now have a beautiful boy who is 10 days old.
The bleeding is probably implantation bleeding and nothing to worry about. As far as having no symptoms of being pregnant, every pregnancy is different. My second one started out so different from my first that I didn't truly believe I was pregnant until my midwife did an ultrasound at my first appointment. It is probably a good idea to see your doctor, but I don't think you have anything to worry about. Congratulations!