Hi Lou, please don't be concerned about fertility based on MB alone - it can be very unreliable for some women, some never get ferns and others get ferns all month long and both of these things fall within the parameters of 'normal'. Maybe if you're not having luck with MB it would be a better idea to try OPKs (once your DH gets home as they can be expensive) and maybe temping as that will give you a lot more information about what your body is doing.
HTH
:-)