If you have already had your period i wouldnt test until you have missed one. sore boobs could be for other reasons and they could be feeling bigger if you've gained a little weight. your probs only half way thru your cycle and would have just recently ovulated so it would be too eary to test just now as implantation wouldnt be for another few days then you need your body to make the hormone to make the test read positive!
Id wait until the day that your next period is due at the earliest x