Is it Very Likely My Fiance Is Pregnant?

We just celebrated our 4th year anniversary together. We've practiced safe sex for our entire relationship until 3 nights ago. A few months back, my fiance began to experience severe pain during her periods, so she got on the pill. She got on Loestrin because the previous medication wasn't working. She has been on the new pill for about 3 months.

Usually she has heavy bleeding and severe cramping. This is how it was until today. Her period began lightly with mild spotting and then moved on to normal flow by day 3. Tonight her period abruptly stopped (end of day 3). She is afraid she is pregnant. Unfortunately, we can't make it to the store right now to pick up a test because all the shops are closed for the holiday. So this is the best solution I can think of for now.

Here is the scenario now that I have given a brief medical history. The other night, we went without a condom. She was on day 1 of her period and is on the pill. Now, 3 days later her period has stopped and we are concerned it may be pregnancy. Is it likely she is pregnant?

Thank you for your time!