You clearly need to get more familiar with the witnesses. I'm surprise you are only voting for 6. Don't be too scared to vote for some bad "witnesses". Your choice will be better than random chance.
Block per day can be seen here. My guess is 2-3 block a day is enough to break even.
https://steemdb.com/@ura-soul/blocks
I don't have a free witness vote right now but I'll consider it in the future.