Im on new medication

Hi my name is alex and im 15 years old. About 7 months ago i got my period for the very first time. At first it started off very light and then with in a matter of 2 days it became that heavy that every 10 minutes i had to change my pad, my undies and my shorts.I had to have a shower along with everytime i had to change beause it would actullay drip down my legs. I was going through about 2 packets of pads a day and changing my bed sheets everynight. The pain that came with these heavy periods is unexplainable. It would get that bad that i couldnt breath propely and that i would be on my bedroom floor yelling and crying in pain because it hurt that much. I didnt tell my mum about my heavy periods beacause i thought it was normal. I told her about my pain though, but she just answered it as me being a teenger and overeggarating things. I had to take about 2 weeks off school because of my period and the pain ( 1 week every month). I was so scared to go to school, because i thought i would "leak" everywhere. My mum started to become a bit concerend but still didnt believe me. I thought there was something wrong with me.  It wasnt until she heard me crying on the toilet and came in and saw it for herself. She was shocked. She said that hers has never been any where near as bad as mine and she is 36 and has 3 kids.  About a week after i went to the doctors. They put me on the pill called levlen. I have been on that now for about 4 months and it has helped alot. Iv put on about 5 kg though, which i hate. Im very tiny for my age and i hate the thought of me becoming a 'fat midget'. I didnt notice my weight gain until i found a text on my mums phone that she had sent to my dad. She had asked him if he had noticed my weight gain. I was devestaded when i found this out. I tried to starve my self but i was so hungry that i couldnt. I went to the doctors today and got some more medication. Im on a new one now called yaz. I was reading about it on here and now im terified. People say that it makes you crazy and that some people have died from the side effects. I read that one of the side effects is depression. I think i may get this from time to time. My dad also has bi-polar. Could i have it? Can someone tell me the side effects and what yaz actually does to you? I need help please! I dont know what to do! Someone help me!