I did at about 10or 11 weeks start at your pelvic bone and move up slowly
Sometimes you have to search for it. Rayd is right. Start at your pubes and move up slowly. If nothing by the time you get to your belly button try slightly on the right or left. Make sure it's the babies it will be much faster than yours. Good luck
Also make sure you're using the ultrasound gel or aloe Vera works too. You won't hear anything without it.
If you can't still get it after what the ladies above suggested bring it to your next docs visit. Your doc will show you how to use it correctly. Theres also YouTube videos how to use it.
I have the same one and I heard it around 11 wks. I'm also a lil bigger too. I noticed I had to apply a good amount of pressure and put it really low like around the line where ur pubic hair ends. The only way I knew where to put it is cuz I had a cesarian 12 yrs ago and just put it right on the scar lol. I hope u get to hear it soon, good luck!
Midwife listened to baby's hb yesterday and picked it up straight away im 10+4 today..hope all is well with you all and congratulations :) x