the possibilities in your case are,
-as you had previous periods on 8th august, there is possibility for ovulation to occur around 25th July, so there chance of pregnancy
-as you had previous delayed period, this time also may be that is getting repeated suggesting some underlying hormonal
so you better consult gynecologist and go for blood test
for pregnancy, if comes negative undergo physical examination an ultrasound
examination to find out the cause for delayed periods.