How fast should FSH levels be expected to increase in menopause

I'm a 43 year old who's been undergoing quite a bit of different health issues here lately. Most recently I had some bloodwork and CTs and will have a doppler on my abdominal artery. They got the CTs back today and will go over them with me tomorrow. However, the dr's office called me today and told me that I'm "in menopause"....I'm quite confused about how/why she would have said this, unless it was STRICTLY based on my symptoms. However, I have no uterus (and therefor no cycles for the last 4 years) and the most recent bloodwork did not include hormone levels. The last hormone level test I had was last july and my FSH was 8.1 I'm just wondering with everything I've read about the perimenopause lasting 4 years n such, is it even POSSIBLE for my FSH to have elevated that high that fast? I'm even beginning to wonder if maybe they called the wrong patient. I was so busy with my stepdaughter today, I wasn't very focused. 

Thank you all for any input.

Dear krista, your hormones can crash overnight! I had full bloods done just after xmas holidays as wasnt feeling very well. Less than 24hrs later bloods came back all perfectly normal apart from slightly elevated white cell count which is normal for me. 24 hrs after that was my first ambulance and paramedics I had such severe chest pain and because I have unstable angina I was certain that I was having a heart attack. No. All tests normal. Told to contact my dr asap. Talked to him next day, he sent surgery paramedic to take more blood and boom! Told ovaries had died and hormones had crashed. So went from completely normal to full meno in less than 3 days! My dr told me that it can literally happen overnight. It is such a shock to the system when it happens. You can be fine one minute then bang headlong into menopause. At least we have this forum to care and share on. There is only a so called normal range of hormones but what is normal to one lady is not necessarily normal to another one. Hope you feel better really soon XXX

As Tina mentioned, each women is different.  I saw an endocrinologist, who had a full period one month, and the next month her estradiol was so low it was unreadable.  So yes, it can happen fast.   For other women, it can be a very slow decline.  

I don't think it's a bad idea to ask for a hormone panel however.  If nothing else, it would help clear things up in your mind.  And please ask for a copy of your labs.  There must be a reason they have told you it's menopause, so possibly there was some testing that they failed to mention.