Loss of pregnancy symptoms

Im 7w6d today and all this week I have not had any symptoms. At 5-7 weeks I had nasuea and breast tenderness. Now I have no symptoms and I'm worried. I had an u/s at 6w2d and saw the heartbeat and it was 87 bpm which also has me worried but my ob said it could be because the heart just started beating. I'm so terrified that I'm having a missed m/c.