Period a week & a half late. 2 negative pregnant tests. sharp on and off pain in lower abdomin. also feeling gassy, any ideas of what it could be?

Premenstrual: These sound like premenstrual type symptoms. The fact that you've had 2 negative pregnancy tests seems pretty solid that you're not pregnant. It's normal to have these types of symptoms prior to a period starting. Ibuprofen, 600mg every 8 hours can be of help for the pain you're experiencing, but it looks like you're already on that? If pain continues, consider seeing a gynecologist.