Pregnancy Symptoms but Negitive pregnancy test... WHAT IS WRONG?!

I started taking birth control 1 1/2 months ago but it is a low dose and I am only using it to prevent pregnancy!. It only bothered me the very first week I took it then everything was normal!. Within this past month I am two weeks late!. A few days after I was late I started to feel like I was going to get sick, manly in the mornings, and I also started to get headaches!. Before I missed my period my breast began to hurt and they still are!. within the past week I have started to feel really tired and at work the other day I had to stop what I was doing and sit down to regain strengths!.
I took a test the other day and it was negative but I am still having this symptoms!.
Should I go see a doctor or take my friends advice and ignore the symptoms!? Could I really be pregnant or is it just from the birth control!?
PLEASE HELP!!!Www@Answer-Health@Com

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