Are Sore Breasts, Tiredness And Feeling Hungry Symptoms Of Pregnancy?

I have sore breasts, have been eating more than usual and feeling slightly tired/ irritable. I thought I may be pregnant but as I am on the contraceptive pill, as well as having taken 2 negative result pregnancy tests in the last 2 days? I am taking Champix and am on the second week, is there a chance that this is causing false pregnancy test readings?