"I guess now I can save money by not having to buy pads and tampons."
...not so fast.
It's highly likely that you're in the Peri-menopausal stage. And, if that's the case, your periods could resume as suddenly as they stopped. To be considered fully menopausal, you'd have to go an entire year without a menstrual period.
The pregnancy test was negative. So menstrual cycle just stops just like that? I guess now I can save money by not having to buy pads and tampons.