Is it normal they couldnt see my baby's heartbeat?

okay..i found out i was pregnant on may 23rd, and i went to the doctor june 7th they run some test and done a papsmear and he said i seemed to be about 8 weeks, but wasnt sure cuz i couldnt remember when my last period was cuz their irregular. 2am thursday morning i started cramping some and i started spotting so i went to the er and they checked me for ectopic preg. and it come out i didnt have that, my hcg level was at 17000 and they said that was perfect, so i called my doctor about 10 and he told me to come in friday and they were gonna do an ultrasound. when they were doing the ultrasound they noticed a yolk sac and a baby but no heartbeat and they said they thought i was just about 6wks, and that everything looked normal. and the reason they couldnt see anything was because it was to early and the baby was up against the uterine wall and they were having a hard time seeing anything..they said the spotting was probably due to the papsmear...is it really normal they couldnt see anything or were they just saying that to keep me from getting upset, im having normal symptoms i stopped spotting and my stomach isnt hurting anymore, im suppose to go back the 22nd to get another ultrasound to see if we can find a heartbeat and im really scared that something is wrong