Please help, im confused?

I had ual with my bf on the 23rd Dec and straight after that, i took my normal contraception, Yasmin. I am now 3 days overdue with my period and me stressing out is making it even worse, could i be pregnant? Im so scared to do a pregnancy test. I have missed 1-2 tablets but woud that mean that im pregnant? I also feel sick and fat, are my hormones playing with me?