I think maybe just continue to BD. I'm in the TTC 1-6 mth thread and am finding that lots of women only get faint lines or none at all even though they are ovulating.
I wouldn't put 100% faith in them. maybe try another 2 days, thats what the box says (test for 5 days).

when your body has ewcms that's the best time. cos that's the mucus plug coming out of ur cervix and now is clear for the sperms to swim into.
Other women in the thread measure their temperature to know when they ovulate. I havent started that yet. maybe next mth, if no BFP this time!

have a read of TTC 1-6 Months May thread even if you're not TTC. there's lots of info there.
take care