The only way to know if you are really having a twin pregnancy is to see it by yourself via ultrasound. An ultrasound done at 5 to 7 weeks is very unlikely to miss an additional baby if ever there is. A fetal Doppler is also used to monitor the baby’s heartbeat and can usually distinguish a multiple pregnancy by detecting more than one heartbeat BUT sounds can be misleading at times, what you think is a second heartbeat might be a background noise or the mother’s own heartbeat.
They say that mother of twins are usually having excessive amount of morning sickness, extreme fatigue and lethargy during the first trimester. This is a pretty much subjective indicator because some experience it while other’s don’t. Having a family history and/or previous multiple pregnancy,the chance of having twins increases. Getting pregnant while on pill and/or breastfeeding gives you the chance to have multiple pregnancy.
Mother’s intuition are sometimes true but we cannot rely on it always. It is always best to take and undergo some medical indicator to know if you are having a multiple pregnancy.