I completely understand where your coming from. My son and daughter both had (have) bedwetting problems long after they were potty trained. I was told that it runs in the family (which my husband did have problems with when he was younger), and that it can be due to a combination of things, either their bladder has simply not matrued enough, or they just sleep too hard and their body doesn't receive the signal to get up when they have to go. That being said this is what has worked for us.
I used a Malem brand bed wetting alarm for my son when he was about 6, or a little under. It worked great! He was done wetting the bed within a few weeks (avg time is 6 weeks). For my daughter I am usuing a Rodger wireless alarm because the sensor placement is a little better for girls and it is working great!
With the alarm, a little beeper goes off (sometimes vibration too) when they start to wet. They are then supposed to stop going, get up and go to the bathroom to finish. Eventually the amount of times that happens slows down and then stops. The first couple weeks you are supposed to be in the same room, or near then so you can help them when the alarm goes off because either they don't hear it (amazing, but true-my son had to be woken up several times in the beginning)or they just don't know what to do. this has worked great for both of my kids.
To go along with that, I try to make sure they have their last meal/snack at least 1/2 hour before bed, and drink only water (small amounts) after that. Milk and soda can actually make you have to go more. And the last thing we do is called "double elimination". It simply means you have them go potty about 1/2 hour or so before bed, and then once again right before they get in bed. This ensures their bladder is empty when they get in bed. Just that one step has helped my daughter have dry nights!
Sorry to go on and on, I just know how frusterating this process can be and want you to have lots of ideas to try from things I know work. Hope you find something that works for you. Good luck!