Brown spotting in first trimester

I’ve been having daily brown spotting for two weeks straight now. I am currently 8weeks, 2days. We had an ultrasound on Friday and heartbeat was confirmed at 164. There was nothing on the ultrasound showing a bleed. Doctor says spotting is common, but daily for two weeks makes me worried. Has this happened to anyone who’s gone on to have a successful pregnancy? How long did your spotting last?