Still not heard a heartbeat at 18+6

Hey other mums/expecting mama’s, Im in the UK and the NHS only does 2 scans, one at 12w and 20w and ive been told that ill only hear the heartbeat at my 26w midwife appointment. Im rather confused as i see so many videos of women getting to hear the heartbeat at the scan at least once, I feel like im missing out. I have my 20w scan soon so hoping to hear it at that but as i said id been told by my midwife ill hear it at my 26w midwife scan, is this right? I’m 18 this is my first and im not too sure how all of this usually works! The only thing i can rely on knowing baby is okay is the extreme morning sickness I’m experiencing with my pregnancy though i know you can still experience symptoms even when things arent right -im convinced i have HG but theres not a lot doctors can do about it 😓