Negative blood pregnancy test but no period for 9 weeks, what could be wrong with me?

Many possibilities: There are many hormonal problems that can lead to irregular periods. Hypothyroidism, hyperprolactinemia, polycystic ovarian syndrome, to name a few. There are medications that can affect your cycles, like steroids. Other factors like stress, travel, weight changes, and exercise can also play a role. It's best to get checked out by your gyn.

Many possibilities: Please see you gynecologist, there are many things that can cause lack of menses, including ovarian cysts, stress, menopause, hormone problems etc.