You're getting a lot of good advice and there is a ton more in the Training forum right here on YT. If nothing else, you will learn that you are definitely not alone in your troubles.
One other suggestion I would make is that you might be giving him too much freedom before he is trustworthy. The thing that I've learned about housebreaking through the years is that if I can set myself up for SUCCESS only, mistakes are very difficult to make.
Coby is 8 months old and just recently got free reign of only his second room. He spent all his time in the tiled kitchen with some supervised trips to the living room. Now, although he stays in his kennel when we are gone, he now has free run of the kitchen and the living room. I will be adding another room in the near future. But by really taking baby steps, I find that I limit the mistakes and celebrate the successes. That seems to turn into more successes than mistakes.
Good Luck!!