HCG quantitative

Hello ladies, need a little help to tonight til the doctor calls in the AM, went in to testing with feelings of lightheaded dizzy and low blood pressure. All in all I have low iron, which we figured with my symptoms and anemia. What is throwing me for a loop is my HCG levels, according to them I'm about 6-7 weeks but I should only be about 5 with my time line. Last period 6/12 positive test 7/4 &7/5 etc.. I found out so early it's hard to believe I'm FARTHER along then I am. What are the chances of multiples? Has anyone experienced this before and still hit the mark on the week gestational. I go in for an early ultrasound if my levels are elevated so ultimately I know the doctor will decide but curious what you think of my current predicament!