20 Days of Eating at a Deficit and No Scale movement!

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I did my first weigh in today, and I'm actually UP half a pound. I'm a 5'8 male at 188 pounds, and have been eating at a deficit now for nearly 3 weeks. I set the goal as weight loss of around 1.2 pounds per week, eating about 10 calories for every pound of bodyweight. The first week of MFP had me slightly higher than that, and I adjusted it down from there. I actually have a solid amount of muscle from previous workout cycles, so I wasn't even sure if 10 cals/pound would be enough.

I just started Stronglifts 5x5, but have been jump roping, or jogging or doing some kind of physical activity on most of the other days. The Stronglifts mantra says you shouldn't do cardio on off days--that your body needs to recover and be ready for the next lift--so I haven't; not sure if I want to add some incline walking on my off days, but I'd also really like to get my strength back.

I work in an office, but switched to a standup desk months ago, so I'm on my feet Monday through Thursday for 8-10 hours a day. I'm not totally Sedentary. I also walk around quite often during the course of a normal workday, and did a bunch of work around my house and garden this weekend I didn't even bother logging, so as to avoid "eating the calories back".

In full disclosure, I ate poorly over Memorial day weekend--was way over for those 3 days. Traveled to see my family to celebrate my Mom's birthday and drank too many beers and had some birthday cake. But at a 5-700 calorie deficit, it's hard to understand how those three days of eating at or slightly above my "maintenance" calories could have undone the other 17 days of eating at or below it, along with all the exercise I've done. Are my calorie targets just off?

Man, I do feel like quitting. It seems like no matter what I eat, my body is trying to keep me in this same weight range, which is not where I want to be. If anyone wants to look through my diary and give me some advice I'm open to it.