I was and still am Bipolar. As I have grown older, it is MUCH more managable. As a teen, not so much. I think there are many factors as to why it is more managable/ less severe.
I became very educated about my illness, after I got over the whole "nothing is wrong with me" attitude. I learned how I cycled and what were possible "triggers" and warning signs of both my depression and mania. I would have long cycles, lasting weeks, maybie months at a time. After i learned to pick up on these signs, I found tools that worked for me to lessen the effects of the depression or mania, sometimes this ment upping my meds, other times it ment extra counciling or extra activity to keep my mind in check. I agree with the pp who suggested intense physical activity. I became almost obsessive at times when it came to my activitys, but it was a healthy obbsesion.
Another factor is the hormonal one. As i have grown, my hormones have leveled out some. Something that helped me as a teen was birth control. Might want to speak to her Dr about that. I think these days they have BC that helps level out all the hormones more so then BC from when i was a teen.
I was hypersexual as a teen, starting from a young age. I hid it well from my family and friends. I had similar behavior to your daughter, though we didnt have texting, but internet chat rooms. You are more than welcome to PM me for more on that particular subject, although I dont have tons of advice per say, just know the behavior and what triggered it for me.
I also got into drugs a bit. Not wanting to scare you, just speaking from experience. It was my way of self medicating, and i didnt do it for plesure per say. Now that I know my problem, I look back to the worst times I had, and I am able to say, hey now I know why i did this or that. I used to be shameful of things i did, but now I know that i was trying to cope with life the way i knew how. I think that is the key. Finding alternate, non self destructive ways to cope. I think the teen years are the worst when it comes to this ilness, but can also be the time to really learn to deal with it. Like i said, you are more than welcome to PM me for any reason, I might not have the perfect solution, but i might be able to offer more insight as to what/ why she might be doing. Also if she ever need someone to talk to I would be more than willing to listen. Sometimes its nice to have someone thats been there, done that and knows what it feels like, that isnt going to judge you. Hope I have been helpfull and best of luck.
Also just wanted to say,
, It takes a special parent to deal with someone with these issues. There will be very tough days, but as you learn, things get better, and the good days start to take over again.