My DD has been waking more and more ever since 12 weeks. I spoke to a health visitor this week and she suggested weaning. I'm not convinced it will help, but I have given my DD a couple of bits of carrot and some green beans to chew on while we've been eating our tea - at least it keeps her quiet while we've been eating!
I'm not sure it will make her sleep any more, but is it possible that she will wake up more?