Hi I know how you must be feeling I have been there too many times. I have been pregnant 6 times and had three lovely boys from them and sadly I have lost 4 two being twins. My first pregnancy when my oldest Son was born was the only one I did not bleed. Please try not to distress yourself too much (easier said then done I know). It is quite common to bleed in the early stages I have found this link for you I hope it helps explain a little bit of what you are experiencing.
http://www.pregnancyinfo.net/spotting_bleeding _during_pregnancy.html
If you start to get any cramps ring your local pregnancy assessment clinic which should be based at your local hospital, tell them you have already consulted your doctor. They are there to help if you have any worries and may ask you to come in early for a scan, I have had scans a 5 weeks you can see what is there even at that early stage.
I hope everything works out well for you,