Interestingly, my doctor said I was not in perimenopause and she also did not mention birth control whatsoever. She was just like... well... let your body get adjusted. FWIW, my OB/GYN is a woman and older than me, so she's probably been through it herself.
Going from clockwork cycles to guessing cycles is not the greatest of experiences. Blood work has been done, ultrasounds have been done (periodically, as follow-ups)... there does not seem to be anything there that points to an obvious issue.