If you really think its the nappy that's bothering him then as the others have said, use a stay dry liner (Minky or microfleece work well). Is there any possibility it could be something else? (Excuse me if this is rude)
My little boy wanted to be fed every hour at that age... Is he different in disposables?
As for being environmentally friendly, he won't need half as many changes as he get older. Extra washing has to be better than a nappy sitting on landfill for 500 years, long after his great great great grandchildren have passed...