On BC pills approx 6 mnths, missed a couple, still get period, sore breasts, preg. tests say negativ

Yes, I've been on my birth control now for approx. 6 months and in the last couple months I have missed 2-3 conssecutive pills in one pack but still get my period, now withing the last month and a half I've had sore breasts (which I never get unless I'm pregnant and trust me I've been pregnant) and I've gotten my period and it seems regular as well but the tenderness in my breasts is not going away and I've taken a pregnancy test and it came up negative but I don't understand what the heck is going on, I would have gone to a doctor but it's impossible to get there with my schedule so that has turned me to you who hopefully have some answers for me. I've also phoned and spoken to a nurse and she does say that urine tests take up to 3 weeks to be determined if you are pregnant and blood tests take a week. I've also been feeling strange kicking feelings in my stomach as if I am pregnant but that would mean I would have to be further along and forsure why would the pregnancy test come up negative. Please help with these dilema's, thank you.