SSS woe

With all the flurry of payments -- tuition, credit card bills, rent, I almost forgot that it's almost time for me to pay my second quarter SSS benefits. Good thing I checked on the contributions I have to make. I was surprised coz it seems that I have to pay a it more for the same income bracket. While I'm self employed and could pretty much choose my own income bracket, I'd like the same level of social security benefits that I am entitled to. Oh well, what do I expect?