I was diagnosed over 10 years ago and have found the same thing,in the first few years i spent days in mania then a month in depression.Then i stopped getting the mania and just got the depression for a few years and now i am going through a one month mania stage with months of depression.
I have noticed it can change in time,i now know what to look for (the sign of a on set) to get help straight away.But have noticed as i get older the mania has changed ten years ago i would go out for nights on end drinking and party and sleeping around,now i notice mania because i start to have insomnia and start researching business ideas for weeks on end with little sleep . I also have not been in hospitial for a few years as i know that thing do slowly get better and one day i will be ok again.
Cycles seem to change as we go through different stages of are lives,did something trigger your mania ? My mania start when i take on to many things like working full time and looking after my son,i can only do this for a while before mania cuts in and i have to leave work .but it has been triggered by relationship breakups,losing people from my life,failure to get a promotion,etc.BP is great for always being unpredictable-when i work out my warning signs etc,they can then change and i may not notice it the next time.Speak to the doctor about your meds and see if they can be changed or upped and remember that you have been through this before and you will get through it again.
Bipolar can change in how it occurs and also one specific type of bipolar may be diagnosed and it may actually be another type. Also a specific medication may not work as well as it did and it may need to be adjusted and/or changed. It would be essential to discuss all of this with your psychiatrist and then they could make an appropriate decision as to how to best help you within their discretion.