Heartbeat increased but slow growth

According to my LMP I should be 7 weeks 4 days. Because I am a high risk pregnancy, I have had 3 ultrasounds already. My last ultrasound the baby measured 6 weeks 0 days with a heart rate of 86. I went in again today (a week later) and baby is only measuring 6 weeks 1 day but the heart rate has increased to 101. It seems like baby isn’t growing but the heart rate improved so I don’t know what to make of it. Has anyone experienced this? What was the outcome?