Heart beat at 11wks 1 day

Well guys i was so excited about my appointment today just knowing i would hear my baby heart beat but because I am obese and she said it may be also still early we didn't hear anything. I am scheduled to go back in a week at 12 weeks and if nothing then an ultrasound will be scheduled I'm very nervous about this has anyone else experienced this??? I miscarried in February really early so now this is worrying me a little...help ?!?!