We used Happy Heinys with my now 2 1/2 year old and we went through about three months where I could not get him through the night.
We used three inserts with the HH and a fleece cover AND then I put him in a wool longie. He looked ridiculous but it worked!
My 9 month old uses prefolds and I use a prefold and a super thick wool cover and he seems to stay dry.
Are you BGs absorbing? Did you check them to see if they need to be stripped?
Here's some info on that. You need to figure out if it's the diaper or just something you have to adjust to for right now.
http://directory.diaperjungle.com/blog/2005/10/27/strippi...
There are a million different ways to strip your diapers...depending on who you ask! :)
I just would do a prewash with vinegar and no detergent and that seemed to help every month or so for a while.
http://directory.diaperjungle.com/blog/2005/10/27/strippi...
Good luck!