If you took all of the pills except the sugar ones like you said and you were due for your period on monday then I am pretty sure you wont be pregnant. It sounds like the spotting you are getting is just the beginnings of your period and it is just a little late which can happen especially since you didn't take your sugar pills. Still the pill on its own is not 100% so there is always a possibility so go and see your doctor who may do a blood test now and then again in two weeks to see if you really are pregnant.
Goodluck