Calories

I like to use the calculator.net calorie calculator. I've found it works well for me. If I put in your stats with sedentary, then it spits out 1810 calories to maintain (plus eat your exercise calories on top). Personally, I prefer to do it that way as my exercise level varies and it means I get to eat more on days when I do a lot of exercise and less when I don't.

If you are just generally lightly active, rather than specific exercise active, then the "light exercise" option would put you at 2074 calories.

So to lose 1 lb a week you should be eating 1310 cals + exercise calories, or 1574 calories. So the MFP estimate seems a bit high (unless the 1900 was your maintenance amount?), but you could be eating more than you are. If you aren't losing weight at 1200, maybe 1300 (maybe? what is the actual average?), then a few things could be happening. Either you aren't tracking every single thing and so are actually eating more calories than you think, or you've been doing this a long time and your weight loss is naturally slowing. Where are you in your journey? If you've been doing it a long time then having a week of break at or near maintenance will probably help.

But if you're not tracking every single thing it does add up - miss out the milk in your coffee, forget the little squirt of mayo on your healthy salad, which was actually 2 tbsp, forget the tbsp of oil in your healthy stir fry for dinner - then you forgot 425 cals which would put you at 1725 - near maintenance, so no weight loss.

I would enjoy a week at 1900 cals and really track absolutely everything, and see what happens.

Reasonable advice from those above, but a single week isn't enough to know what's really happening. A new eating routine, especially if combined with a new exercise routine, can result in water retention weirdness (that masks fat loss on the scale), different amounts of waste in the digestive track (same effect), etc.

It's a good idea to go with a new routine pretty consistently on average for at least 4-6 weeks, or one full menstrual cycle for those who have them, to see the multi-week trend of weight. Weight loss isn't linear, so we need that much data to get a good understanding of our average weekly weight change. A week or two isn't enough, especially the first week or two.

You don't say how long you've been at it without losing, BTW: That timeline recommendation applies there, too.

As an aside, I started here at just a bit above your weight (183), same height, much older (59 at the time) and with my then-current activity level I would've lost at 1900 calories gross intake, though somewhat slowly. I admit I'm a good li'l ol' calorie burner for some reason, more than usual for my demographic, but I tried starting out at eating 1200 plus all exercise calories - so 1400-1600 most days - and found that way too low. I lost weight faster than reasonable, got weak and fatigued. Even though I corrected quickly, it took multiple weeks to recover back to normal. No one needs that.

I hear and understand that you're not losing weight currently, but please consider whether you've been at this for the 4-6 weeks or one full menstrual cycle that it takes to see the actual trend of body weight, not just the usual misleading day to day multiple-pound ups and downs on the scale.

Fast weight loss isn't better weight loss. Healthy weight loss, something we can stick with pretty easily long enough to lose a meaningful total amount of weight, is better weight loss. As a bonus, that approach can better help us learn the new habits we need to stay at a healthy weight long term, which is the real golden prize on offer here. (I'm saying this from the perspective of 9+ years now at a healthy weight, after around 30 pre-loss years of overweight/obesity.)

Best wishes!