It is not normal not to have your periods, and so I would suggest more elaborate tests to find the cause and also the initiation of medication to help normalize your cycle.
The uktrasound scans you had might have to be repeated as a lot can change with time and may be thus time they can visualize the cause (if present). Along with this a check on your hormonal
level would also be required.
You are also experiencing a hightened sense of smell, which is usually a common side effect of medication or even hormonal imbalances. This adds to the list of reasons for an elaborate evaluation.
Hope this helps.