Hoeboy,
I feel your pain man!
I am number six out of eight siblings, and for years had to live up to the successes of five older brothers. It wasn't bad enough that I heard it at home, but also from the teachers at school that taught them in previous years.
It took me a long time to realize that I am not like my older siblings, therefore I don't have to live up to those expectations. Once I learned to be myself, I became better at achieving MY goals. Success is measured in how well you live YOUR life, not how you live up to others expectations.
You have the right attitude; you love your parents. They weren't given an instruction manual when you were born, I'm sure they did the best that they could. You may not have enough time to show them your successes, but if you take confidence in yourself and follow you OWN dream, you may just gain their respect. They may just respect you for being the best "Hoeboy" that you can be rather than trying to be clones of your brother and sister. Why would you want to be as good as them, maybe you are better?
Trying to become successful to prove someone else wrong is not the best motivation. The only person you have to prove anything to is yourself.