“Sore breasts” are a very subjective symptom of pregnancy; the presence of this symptom or lack thereof doesn’t really indicate anything. Spotting and abdominal cramps during pregnancy are symptoms that should be taken as very serious signs of possible miscarriage. Since you are not experiencing these symptoms, we can’t talk about possible miscarriage in your case. It is true that hCG-levels increase rapidly during first 7 weeks of pregnancy and if they stop increasing during that period, we interpret this as a bad sign for continuing fetal development.