Weekends off = four pounds?

Looking for some insight! I've been doing 19/5 IF since March 17 and I'm super happy to be down 12 lbs. But the last two weekends threw me for a loop.

Two weekends ago, I took a tiny break. just almond milk in my morning coffee and three meals instead of two. On Monday, the scale was up 2 lbs and stayed there all week. Then this past weekend, I had a wedding and a BBQ, so I skipped weighing myself for my own mental sanity. I loosened the IF window but not too crazy. Monday morning... up another 2 lbs

I finally lost that extra weight today after 12 days of back to the routine. What happened here? There's no way a couple of normal meals equals 2 lbs of actual weight gain every time, right? Help me make sense of this!