the pill can make you skip a period or be late. go to the doctors and tell them yor problem, if you are worried about possible pregnancy ask for a blood test. some hpt don't show positive for some people for a few weeks after implantation. it happened to me... i was on the pill (did miss a few though) missed my period and took a test (neg) then one 2 weeks later and it was positive, i was 6wk 4 days. it is possible. but as soon as we start to have sex we worry we are pregnant!!!its only natural.
hope this helps
emma
also... i noticed my cervix has been really high up lately.. i would say for the last week or so.. not sure if that is normal or contributing to my missing period. I know its supposed to be high when your ovulating but i'm not sure how long its supposed to stay up there..