I'm not qualified to answer your question about the location of your uterus, but if you are having pain and feel like there may be a lump, you definitely need to see a doctor – preferably a gynocologist.
You mentioned that you've tried losing weight by eating only breakfast then drinking herbal tea for the rest of the day. Actually, only eating one meal a day will make you more prone to gain weight. When your body doesn't get food at regular intervals, it slows down your metabolism in an effort to conserve energy. The slower your metabolism is the more easily you'll gain weight. The best way to keep your metabolism at the right level is to eat small amounts of food several times a day. Of course, avoiding sugar and eating more nutritious foods is essential, too.
I wish you the best.
Karen