I suppose that amount would be different for different people. Fortunately the figure my food tracking app came up with seems to be fairly accurate, but if it wasn't I would have to use trial and error until I got the results I wanted.
I use the myplate app, which bases it's numbers on my height, weight, and estimated daily activity level. I keep my phone in my pocket and allow it to log my steps every day, so I set it to the lowest activity level and let the calories burned through my daily movement count as that. Because of that what I'm allowed to eat every day will sometimes vary by as much as a few hundred calories depending on how much walking I did that day. I must be VERY active, because looking at the iphone health app shows me that I have averaged over 10,000 steps per day over the course of the last month. That doesn't count my workouts, which I also add into the app every day. All together I pretty much always am allowed to eat close to 3000 calories per day while still losing weight.
All of these apps and calculators are assuming a certain baseline amount of calories burned even if you do zero physical activity. For me, that number is around 1800 calories. That means if I do nothing but lie in bed all day I can eat 1800 calories and probably still stay the same weight. Being active throughout the day drives that number far higher. Close to doubles it in fact it seems. I literally would not have believed this if the proof didn't show up on the scales every week though. That's the thing. You can calculate all you want, but in the end you check your work by checking your weight. That's where the proverbial rubber meets the road. The fact is that I have followed these numbers and have consistently lost or gained the amount of weight I was supposed to be losing or gaining.
Of course all that goes out the window if you happen to be someone who, for whatever reason, burns significantly fewer calories at rest than these calculators estimate. You could be one of those people. There's also the possibility that you are off in your estimates of either your activity level or the calories you are consuming as well. I would start with the latter assumption myself. Start weighing everything you eat. Endeavor to choose the most accurate entry for what you are eating every time. Assume fewer calories burned through activity and exercise.
As far as what "enough" protein is, well there's a lot of different theories on that. I subscribe to the "1 gram per pound of lean body mass" and "more probably doesn't hurt" schools of thought. That puts me at around 150 grams per day at my current bodyweight and estimated bf%. So I try to hit 150 grams at a minimum every day. That's not hard to do, and it leaves me lots of room for carbs every day if I want them. The fact is that when I take in significantly more than 150 grams it's usually because I ate particularly clean that day, trading sweets and starchy foods for lean meats and vegetables. Once again, results are ultimately what matters, and I've been very happy with mine. If I wasn't, upping my daily protein intake would be one thing I'd probably look at.
