What's wrong is that the STEEM price is very sad lately, and it drives the value of all upvotes on the blockchain.
Current weekly income per SBI share is about 0.009, and you post 7x per week. With 8 shares, you should see (0.009 * 8) = 0.072 weekly or (0.072 / 7) = 0.01 per post. That's in line with what you're describing.
Thanks for the answer.