Could my OB be wrong?

I suspect I am about 6 weeks pregnant. My OB has been tracking my hcg levels that haven’t been doubling like they should. I noticed some light pink spotting on Thursday and then some brownish discharge yesterday. I saw my OB and he said it’s early signs of a miscarriage and that I would just have to wait and let it happen. It sucks knowing that this is going to happen and I have no control. Is it possible that the doctor is wrong and it’s just implantation bleeding and my numbers are just slow at rising because it’s so early in the pregnancy? Ive read so many different things and idk what to think or how to feel. Can anyone help put my mind at ease???