I'm 17 years old. I started taking birth control to help lighten...

I'm 17 years old. I started taking birth control to help lighten my periods and reduce cramps. I also thought it would be nice to know exactly when they were coming. Back in November (07), I started taking Yaz. I bled through the whole first pack. I bled halfway through the second pack until the end. I bled halfway through the third pack until the end. By the end of the third pack i already had a new prescription lined up for ALESSE. I started taking Aviane, which is the generic version of Alesse. I started bleeding on the 13th day of my first pack until the end. I'm on my second pack and started bleeding on the 10th day. I called my doctor and she said I needed more proestregin. So, she prescribed Loestrin. However, what she prescribed me is the the 21 pills with the 7 day period.. But I have free samples of Loestin with 24 pills and a four day period. My question is, does it matter which one, like, will the length affect anything? After reading some of these posts it freaked me out, but everyone responds differently. I'm going to give it a shot when this Aviane runs out. Just thought I'd share my experience with other pills. Funny thing is, I have two friends who take Yaz with NO problems, and two friends who take Aviane with NO problems. All these girls are different sizes, weights, taking it for different reasons.. so once again, it affects everyone differently. Good luck, ladies.