I've also got BG and HH, the only thing that has worked for my is my w.machine that will do a 95 degree wash (front loader) - I strip wash the inserts only (don't do the PUL about 60 as it will wreck them) on this every 2months or thereabout and it fixes them - no bicarb etc. Sorry this doesn't help, but I also wash a friends inserts as her machine is like yours. 10mins in the dryer will get them fluffy but I don't bother as it doens't seem to assist performance - and there not against bubs bum anyway.
I know there is a commercial laundry in Brisbane who will now wash MCNs, maybe there is one in your area of find a friend who has a machine that will do a hotter wash.... Alternatively you could do what my mum does to tea towels and thats put them on the stove top in a large saucepan and give them a nice hot bath!!!! Probably not recommended by the manufacturer though!!!