My period is a little off?

I have been having a regular period while taking the pill for 4 years. This last period was very light, almost no need for a tampon, I just used panty liners the whole time, and it only lasted 3 days when my usual period last 5 to 6. I usually have at least one day where I have a heavy flow and the rest is fairly light. I've never had a period like this except for when I first started the pill and I missed a lot. I take my pill nearly perfect every night. It may be worth noting though that me and my husband had unprotected sex a couple times in the past 4 weeks.

Side note: I missed my pill one night but took it immediately the next morning. I'm on a combo pill so the hormones stay in my system longer than just an estrogen pill.

I want to be pregnant, but my husband wants to wait a couple years before we start trying. I'm trying not to get my hopes up since it's extremely unlikely I'm pregnant. Could there be another explanation for an abnormally light and short period?

Update: Took a pregnancy test, and it's negative.