It's not uncommon to have long periods of Depression, being on a mood stabilizer is typically needed. Many people with BP I have to be mindful that AD's can cause mania. I personally can not take any type of Ad as it puts me right into a hellish mania or mixed episode.
It's so hard , often impossible to think about getting out of bed when depressed , but sometimes you just have to give yourself a swift kick in the backside, force yourself to go outside, even a 15 minute walk a day can help with depression.
Have you had a complete physical with blood work done recently? If not , please do to make sure everything is in a good range.
Vitamin D is often low in Bipolar people, Might want to add that if your spending the majority of your time in doors and in bed.
I hope your feeling better soon. Welcome to PC