Anyone have a stepmom or is one? Can you please help me?

My dad got remarried Summer 2006 & my dad, my stepmom, step sis and I have lived together since May. The first couple of months were tough because I had disobeyed some strict rules set by both parents...but they said all was forgiven. My step sis is 8 yrs old, and of course is the center of my s.mom's attention...I am 17 & most of the time she acts like she doesn't care about anything I do or say, (good grades, sports yr round, outstanding friends, work) Everytime I try to help around the house (often) it seems like what I do is not enough. The worst part...I feel like my dad is becoming the same way...I used to be perfect to him, & now, nothing is quite good enough, or how I supposedly NEVER have time for the family, (sports, school, work) I also have to visit with my real mom too! How can I make her like me...my family means the most to me & I can't stand to be just tolerated. What can I do to make her care about me....or am I over my head?