Suggest Treatment For Missed Period With Stomach Bloating

Hi Im 35 pcos. 3 kids through ivf. Last period 7.1.14, im 9 days late. Took a home test it was negative after 3 day missed period. For the most part I am regular maybe being 1 or 2 days off monthly. I am worried because I gained 5lbs in 2 weeks and my stomach is extended and very uncomfortable and bloaded. In other words I look pregnant. What can be wrong with me?