Possibly over thinking

Olivia • Happily engaged and expecting our first baby♡
So I went to the hospital yesterday for severe migraines. They used the Doppler to check the baby, and it took a lot longer than usual to find the heartbeat. (I'm 15w3d) But when she got it, it was very faint, but baby's heart rate was 156. She said it's just because baby was squirming all over the place, and the baby sounds fine. But I'm still worried. Is it just me over thinking? I'd like some opinions before I call my GYN.