As this kind of heavy bleeding u never experienced before, it is better get ur pregnancy test done at home. Even if u were pregnant, it looks like it has beed aborted on its own as ultrasound does not show anything. Such kind of bleeding can happen with hormonal imbalance which can not stop with pause tablets. It needs hormonal treatment to stop such kind of bleeding in the form of oral contraceptive pills for 3 months period
As you may know, you are perimenopausal. This refers to the time before menopause when hormone levels, particularly estrogen, begin fluctuating. Perimenopause occurs, on average, about four years before actual menopause. Menopause is timed as the date of the final period, confirmed after periods have been missed for 12 months.