It could well be doglady, but try not to get your hopes up too much just yet. It could possibley be that, if you are pregnant, your body isn't producing enough of the hormone for it to register on the pregnancy test just yet. The discharge and sore breasts sounds promising, although I always had sore breasts around the time of the month before I got pregnant.
I know how hard it is to wait, I'm a very impatient person, but if you can give it a week from when you did the previous test.
Good luck, please let us know how you get on x