Is "withdrawal" bleeding from plan b counted as period? if i just ended lmp a week b4 that.. and could it make expected period late ?

No: A normal, regular menstrual period is counted as a period. Other types of vaginal bleeding related to changes on hormones, such as taking a hormone pill like Plan B, are not real menstrual periods. However, the hormones taken will alter the natural cycle for 1-2 cycles, causing the normal menstrual period (the expected one) to be different. Cycles should be back to normal in 1-2 cycles.

Plan B: Any increase in estrogen and progesterone (Plan B is just hormonally active oral contraceptives) can cause minor bleeding when stopped. If you took "Plan B" seven days after your period ended ( day 10-12 of your cycle ?) remember Plan B is not "100%" protective, so if your period is "late", obtain a serum test (HCG) to be certain.