please help!

Rebecca
Hi guys I really need your help, I've been to two doctors this week and both didn't help me in any way.. :( so last month I missed my pill in a total of 7 days but I doubled up in my pill for the days I had missed, I had slight bleeding for 24 hours and that's  me and my boyfriend have been having unprotected sex for the last year and a half ,  now I have been getting very bad migranes on the left side of my head and my pereoid is 18 days late :( I've taken 3 pregnancy tests and all have come out negative! I'm really scared and I feel so alone as none can help me :( please can anyone help!!