My first time on contraceptive (minesse) im on the third white pill still hvnt got my period. should i be alarmed.

This can be ok.: This can be related to when you started the pill pack, if you used a first day of cycle to start your pills, this is fully expected. A first cycle day start of pills, allows for pregnancy prevention, the fastest possible. Cycle may continue for a few days, similar to your usual flow. Each pill pack will result in lighter flow each cycle, continue pill packs without taking any breaks.