low heartbeat

When I went to my appointment yesterday I noticed that the nurse was reading the heart rate of the baby on the ultrasound but didn't turn on the volume so that we can here it. I didn't think anything of it. So I get home and just so happen my fetal Doppler came in the mail (I wasn't expecting it till next week) so we ran out and got some batteries, went home and tried it out. We heard the heartbeat right away, it was amazing considering I ordered it from the wish app and was skeptical about it. I wanted to know how many BPM so I googled. I counted 14 beat in ten seconds so that's 14×6=84bpm right. isn't that a little low for 7 weeks? does anyone know anything about this? I read that normal should be 90 to 100bpm. Maybe I'm just over thinking and if there was a problem I would like to think my doctor would have told me.