High risk!???

Ive Ben going to my doctor since finding out I was pregnant. There is a site my doctor has to were you can see your medical history from that office for that day and every time you go. So I went on it says high risk. One visit and the next it says high risk. III obesity ! I am 5"9 currently at 156 I started off at 152 (I didn't loose all baby weight form previous preg I was breastfeeding) but im 21 weeks today and I lost 4 lbs the visit before last. so ive Ben doing really well with my weight. with my other pregnancies I would of gain about 20lbs by now. But! My point is ! Why is it that im high risk. And she has NEVER! discused it with me im even going to a high risk clinic for my anotomy scan. What should I do because im mad and im going to confront her but why would a doctor do that ?