Aww, congratulations! Honestly, ultrasounds are pretty reliable by third trimester, pero may super small chance pa rin na makagulat ka sa delivery room, I've heard stories! Haha, pero most likely girl ka talaga based on what your OB said. For X names, some really pretty ones are Xiomara (very unique!), Ximena, or if you want something more Filipino-friendly, Xenia. My personal fave is Ximena kasi it sounds strong but still very feminine, pero go with what feels right sa heart mo!