Possibility of twins?

Has anyone had a scan around 5 weeks, shown one sac, and then later found out that they were having twins?
This is baby number 4 and I can not shake the feel that there is two in there, few reasons, morning sickness has been instemse all day, all night, can’t eat or do anything since week 3. My HCG levels are through the roof! Already have bad fatigue and leaking breasts, plus this instinct that tells me there’s 2! I don’t want 2! I want one healthy baby but I know we don’t always get what we want. My scan I had was done because my pregnancy symptoms also through off a chance it was ectopic, cramping (ligament pain) etc which also I seem quite early to be getting ligament pain.
So people with twins, tell me your tales!