12 weeks

I'll be 12 weeks on Saturday, and have my appt this Friday. Last time I had a ultrasound was at 7 1/2 weeks, and baby had a perfect heartbeat. For some reason I'm still so scared I'll go in to find out baby isn't growing. I've had mild pregnancy symptoms (the whole time), no bleeding. Am I over worrying? I had a loss in December, but nerve even saw a heartbeat. Hoping my babe is growing well.