Sonoline b fetal Doppler

Michelle? • I have a 3 year old son and just got my bfp for baby #2!!!❤️❤️❤️
I found my babies heartbeat at a little over 9 weeks. Im now almost 11 weeks and haven't been able to find it again. Has this happened to anyone else? I thought once I found it id be able to find it again pretty easily since I knew the area he/she was in so now I'm a little worried.