Question on heart rates.

Ashley 🐘 • My name is Ashley. Married the love of my life and best friend 1/11/14. Baby girl Scarlett was born July 30! My world💕
So I went to the doctor yesterday and my doctor said I'm 10 weeks pregnant. And the heart rate was 157 BPM. But everything I have seen in Google says that at 10 weeks the heart rate should increase up to 170 BPM and then decrease after the tenth week. Has anyone else gotten such a low heart rate at 10 weeks before? Is that normal? I'm a little worried about this. 
My 10 week ultrasound.