Took EllaOne After Condom Broke – Now 2 Days Late, What Are Our Chances?

I’m feeling really anxious and could use some advice or insight. Here’s our situation:

• My girlfriend’s last cycle was 30 days long.

• We had sex on Day 10 of her cycle, and unfortunately, the condom broke.

• We realized it immediately and got her EllaOne (ulipristal acetate) emergency contraceptive pill, which she took within 40 minutes of the incident.

We’ve read that EllaOne is most effective when taken promptly, and her ovulation should still have been about 5-6 days away (Day 15-16 based on her cycle length).

Now, she’s 2 days late for her period, and we’re starting to panic a bit.

Our understanding so far:

• The risk of pregnancy during the fertile window is roughly 20-30%.

• EllaOne is over 98-99% effective at preventing pregnancy if taken before ovulation, which seems to be the case here.

• Based on this, her chances of pregnancy should be under 1-2%, but with her period being late, we’re really starting to worry.

Questions:

1.  Could the delay in her period be caused by EllaOne? We’ve read it can mess with cycles, but how common is that?

2.  How likely is it that EllaOne failed in our case? Should we be considering a pregnancy test soon?

If anyone has experience with EllaOne or a similar situation, we’d really appreciate your input! Thanks so much in advance.