can’t hear baby’s heart beat on doppler

so i had a doctors appointment two days ago and baby was fine. I heard the heart beat on the fetal doppler the night before, but now when I try and find it (i’ve tried this morning and last night) i can’t find it. has anyone ever had this problem? i’m 11 weeks and 4 days. I’m also scared that pressing down on my stomach is gonna hurt the baby but now i’m anxious and wanna find the heart beat. when we checked on the ultrasound the baby was moving a lot and was upside down so maybe that hss something to do with it??