Need some weightless advice

[ArcaneArts]

I have no idea what I'm doing. I recently started working out because I didn't want to buy a whole new wardrobe but nothing was working so I combined things and still not getting the results I want. 

I am looking to slim down. Not see the numbers in the scale go down as I know that gets complicated with muscle mass. I'm trying to intermittent fast ( though the best I've been able to do is 12:12), get at least an hour a day on the treadmill (was advised this was best for slimming down), and I've been eating healthier while adhering to a calorie deficit. Normally my deficit (between MyFitnessPal and Fitbit) is about 1.5k-2k by end of the night. I do a weigh in once a week at the same time and MyFitnessPal says I should be going down and I went down like 12 pounds last week and got curious and checked middle of this week just for the fun of it and was up 10 pounds again. I also use a measuring tape to measure stomach and waistline and there hasn't really been a change there either, (though my weigh in isn't for another 3 days).

Any advice on what I can do to slim down? I'm fine with gaining muscle or anything like that I just don't want to buy new clothes.

[Tourny]

You’ve probably got a few things at work there, chief among them will be water weight and scale variance

water can easily and rapidly account for weight swings of around 7 Lb

if you move your scales or are using different sets, changes in calibration can cause fairly significant drift.

you shouldn’t realistically expect more than 4 or 5 pounds loss a week at most.

although if you “don’t know what you’re doing”, running a daily deficit of 1500 to 2000 calories isn’t a good idea. Far too aggressive.

Weight loss takes time and patience, 1 or 2 weeks isn’t long enough to establish whether what you are doing is effective. 1 month minimum.

[Baltoscott]

Agreeing with @Tourny A week or two is way too short a time frame.

As far as weight tracking goes, changes in water weight can be huge, but they will average out over time. If you weigh in every morning but focus on changes to your weekly average, instead of individual weigh-ins 3 or 7 days apart, you'll get a much better idea of what is really happening. Trendweight, link in my signature below, is free; it can link to your fitbit account and it will help you see your trends even better.