it is very much possible that u are pregnant.
if u had contact during the ovulation period u can conceive.
well bleeding in first trimester is possible ...it is called as implantation
bleeding in which patient bleeds on the day on which menstruation
is expected ...this can occur even if u are pregnant ...the only thing is bleeding uantity might be less.
u can do a sonography
and b hcg scan for confirmation of ur pregnancy
for which u need to consult ur gynaec.
or secondandly ur periods might be delayed and all ur symptoms might be premenstrual tension.