Doppler @ 9 weeks

I know it’s super early (9w5d) to use a Doppler but I do have some loose informal training on them. I found a very quiet heart beat with a rate of 150-160 and then it suddenly went away after about 15 seconds. It was difficult to determine the sound (whooshing wind vs horse gallop) but it was clearly pulse and much faster than my own. My placenta wouldn’t move right? So I can safely assume that baby?