If i haven't had my menstral cycle in six week, could i be pregnant?

May be: U can do pregnancy test to find out.

Possible: Pregnancy is certainly the most common reason for a missed period when sexually active. An anovulatory cycle (your ovary just does not release an egg that month), thyroid conditions, rapid weight fluctuations, extreme exercise, stress, etc. Are all other causes that may be possible. If you keep having sex unprotected, check preganany tests, otherwise if you miss your next one too, see dr. For eval.