I'm in a similar situation. I feel like you described pretty much what I'm going through.
It is hard to find your purpose in life. Maybe right now you need to regroup, find out who you are, what you want, work on building yourself up and focus on the goals of staying stable or as stable as possible.
It takes time to adjust to the mood swings and knowing its bipolar and knowing that you have to be on just the right meds and have just the right coping skills to get better, but you can make it.
When you feel like you aren't doing anything with yourself, you care about that or it wouldn't bother you and you can use that to your advantage to motivate yourself.