Bleeding

I'm about 3 weeks pregnant and I've been bleeding for about 4 days now and the nurse said I could just have implantation bleeding and that's probably it, but my boobs aren't sore anymore and I feel like I'm bleeding way too much. It's like a light period. I'm worried and i don't know what to do. The doctor also said that my progesterone is really low and I had to be put on a compound.