Yes. Possible. Hindi lang naman semen per se ang nakakabuntis. Nakakabuntis din ang pre-cum. Wait it out for another week, if hindi ka pa rin magkakaperiod, try another PT. Sometimes PT cannot detect super early pregnancy. If negative sa PT after a week of waiting and wala pa ding period, have yourself checked by your OB dahil hindi rin naman normal ang delay sa periods lalo na kung regular ka.
Pwede yun.
Gabbi