8 weeks post partum spotting, pregnant again??

I am 8 weeks post partum, bled for 2-3 weeks post partum then stopped and never had my period yet. having brownish spotting for 2 days. Had unprotected sex 2 weeks ago and again 4 days ago. 2 negative home pregnancy tests and 1 negative blood test. Doctor said if my period doesnt start in a week come back for another blood test bc it could be to early to tell. please tell me this is normal and i am not pregnant again. Thanks