Just Over Week Ago I Had My First Ultrasound For

Just over week ago I had my first ultrasound for my pregnancy. I was 7 weeks, but the fetus measured six weeks. So I was then told I was six weeks pregnant with the due date of 23/5/19. Had a 105 bpm heart rate from memory. I had all day severe nausea for a week following this, extremely sore breasts and lots of little twinges around my stomach, abdomen etc. I am currently 7 weeks 3 days pregnant, and the nausea has gone away almost entirely, and the pain in my breasts is lessening and the twinges aren’t as often. I’m scared about a possible missed miscarriage