Too much of a good thing?

I hope this thread doesn't sound like complaining, because I'm really just looking for some insight. This past week was not my top week. I only had a decent workout on three days, and on Saturday I did a "vertical marathon" (1,034 steps). I'm not really counting that because it only took me 10 minutes :happy: I also went over on calories a few days. So what I was hoping for on the scale today was no gain. What happened was a 2.5 pound loss! Huh?? Since January 11th, I have lost 13.8 pounds, and a few more than that from my absolute peak. Now the two things that concern me--have I really lost this weight or is my scale part of an evil plot? and am I about to crash and burn with a gain or a horrible plateau? My husband has been saying that he's noticed my weight loss. My pants are SLIGHTLY looser. In the mirror, I've noticed a small change. But I guess I'm expecting more for 13.8 pounds. Any insight on these large and continuing numbers?? Thanks.