What Causes Delay In Periods And Vomiting?

ive missed my period and i recently lost my virginity.Im also on the pill im up to mid way threw the red tablet and still no period.
im worried i might be pregnate but the only thing was he didnt get it in the second time we had sex and he was wearing a condom
my mum says its because ive been really sick lately,but this has just been colds and coughs and only when i cough to hard stomache bail is vomited up. please tell me im not pregnate