J.C.
You are not alone. I have four boys. My oldest are 9 & 10, I also have a 3yr old and a 2 yr old. My two oldest both wet the bed. They finally stopped about 6 months ago, at the same time. We tried everything as well and nothing worked, since there was nothing medically wrong we left it up to them.
My husband and I told them they were too old for this and that they needed to change it.(Not harshly, lovingly) We wanted them to know that they were in control of their bodies and they could change it if they wanted to. We then said we weren't buying anymore pull ups. We would finish what we had and that was it. They went to bed about 10 pm so we were very strict about the new rule of "No drinks after 8 pm. No exceptions." We made sure they went to the bathroom 30 minutes before bed and again right at bedtime. If they wet the bed they had to wash all the sheets and blankets themselves. They had to get the carpet cleaning machine and clean the mattress themselves (this was a real pain)and then spray the area with urine spray (they have a pretty good one in the pet section at the dollar tree).
We never said anything negative about it, just reminded them very matter-of-factly to do these chores each time it happened. They hated having to clean it up themselves, they also hated not being to have a drink when they saw everyone else in the house with one. So I told them when they stopped wetting the bed for 6 weeks straight we would remove the "no drink" rule. Within a month they were both staying dry 90% of the time. Every time I heard someone get up in the night to go to the bathroom I would get up too and praise them, let them know they were doing great and they were really growing up.
Within another month we never worried about bedwetting, the boys were able to spend the night at friends' houses without a second thought. I know two months of bedwetting without pullups doesn't sound fun, but it was worth it. My 3 year old doesn't wet the bed at all. When his brothers quit, he quit. We don't even think about it if he has a drink before bed. That's nice!
I hope this helped.
P.S. We bought them a new mattress when we were sure they were done having any "accidents".