Need Help And Advice

Okay so I've been on the combined pill Yasmin for 4 months now and at the end of each course of pills I have spotting then the moment i stop the pill for the week off I start strait away but this time its different I spotted a little before I stopped taking the pill as usual but then when I stopped...nothing...I'm three days late now I did a test and it came back negative but i dont know if it would work yet...I only missed one pill this month and it's the only time I've missed one...I've fell pregnant on a different combination pill before could it be that I'm pregnant while on the pill again?