Pregnant after miscarriage?

I miscarried on January 28th, 2017, I was roughly 7 weeks pregnant at that point. I did not have to have a D&C or anything like that but I lost the baby for sure. I was warned not to have sex for six weeks but of course, my stupid self did it anyway, 2 days later -_- unprotected. I have not had a period since my miscarriage and I have breast tenderness, thick lotion like CM, and nausea. Could I have gotten pregnant? I tested @ what would have been "3 weeks" if I am pregnant and it came back negative. Any advice? (Besides testing again) just want to hear opinions.