What you're describing is very similar to what I experienced just prior to my FINAL period three years ago. Yes, periods
can come every two weeks. The intervals between periods
can be long or short. Basically, the cycle becomes really unpredictable and irregular before it ends completely. Not fun, since it seems like you have to carry tampons or napkins/panty liners with you ALL THE TIME, not knowing when it could sneak up on you again.