Help, I feel like I'm falling apart!

I lived with my grandparents my whole life, and a few years ago my grandpa got alzheimer's, and it's really tough. On top of that our family has a history of bipolar disorder and depression.



I'm like most teenagers in that I am a night owl. I am naturally awake late at night and phsically cannot sleep earlier without a sleep aid, which drugs me up so much(even a small dose), I wake up late on school days.



Basically I have been sleep deprived, and I think it's making whatever mental problem I have worse. I often have EXTREME high and low periods.



I always feel like I can't concentrate, and I have random fits of anger and depression (crying a lot and even feeling like being violent). I feel like that I will lash out unpredicably one day, and I'm scared. I don't want to be crazy?



I go to therapy, but I must be good at hiding how crazy I feel inside, because my therapist assumes it's because of my grandpa's alzheimer's that I'm depressed.



Please help! How do I tell my therapist?! I can't open up to people like I used to! I'm becoming antisocial, and turning to food for depression... I feel like a failure. I can't even do as well at school anymore.