4 weeks pregnant and spotting

I got my bfp yesterday since I have spotted brown only when I wipe off and on. I'm about 3w6d so very early. I have a history of low progesterone and miscarriages that occur around 6-8 weeks along. I just started my progesterone bills 200mg. But my question is since I'm already spotting is this progesterone going to help stop this and prevent a miscarriage from happening? Obviously I know if a miscarriage is already underway it wont. I just need words of encouragement and any success stories. Thanks.