First ultra sound!

Meaghan • Just had my baby at the end of Sept 💗
Had my first tv ultrasound at 6 weeks, 4 days due to being high risk. Saw the little beebs heartbeat and heard it! 126 ! Is this a good rate? Also was measuring at 6week, 2 days... Is that ok? This is my first pregnancy so so worried!! 
Also since the appointment I have started to get sharp pulling and cramping right below my belly button... Is this normal? So nervous!