Possible twins?

So I’ve been finding two heart beats (both above 140 so definitely not mine and second baby so I know what to look for) consistently since 9 weeks. I’m a little over 12 weeks now and had first scan two weeks ago showing one but she was really quick. I’ve got a second scan Monday when I’ll be 13 weeks because I called asking for their opinions on why I’m finding two but they were no help and I could hear their eyes rolling on the phone so I asked for another appointment to make sure. Twins run in my family, ever since I got my positive ivebeen feeling like it’s twins. I also had a dream that I was first having a girl, then a week or two later dreamt of twin girls. I’ve been terribly nauseas this pregnancy and super tired, all symptoms started a week after my positive test (which showed positive 5 days after ovulation. I was tracking) while with my son, i had the most amazing and easy pregnancy. Just wondering if anyone has been through this and found out there was a twin hiding or their dr just wasn’t thorough enough??