12 weeks 6 days and didn't hear heartbeat

I had my doctors appt. today to hear the baby heartbeat but was so disappointed when we didn't get to hear it!... One of the first things the nurse said was "we may not be able to hear it because you'll still a little early" but i really was hoping to hear it just to ease my nerves a little! I'm just super bummed because my next appt. isnt until 4 weeks from now which is going to feel like a century!😢😢 I just really want to know that everything is alright