Why isn't this working?

Are you drinking water? If not, get your 8 glasses a day in. Also watch your sodium and make sure it is not high. Those 2 things messed up my weight loss. It looks like you eat pretty healthy.

By the way - your profile pic is awesome.

A lot of maybes in there. If you don't know for sure, you won't know.

I'm still fairly new to MFP but I think I must be wrong because I don't seem to be losing any weight. I started a few months ago and actually seemed to be losing a few pounds but then went on a vacation and stopped counting but didn't gain or lose. Then I've come back here with more commitment than when I started and have kept under my calorie count for the past 20 days (which I think may be pretty low because MFP sets my daily goal as my BMR, so I try to eat back exercise cals so I don't starve) but I may be even be gaining. And maybe this is part of the problem but recently I feel like I have to stuff myself to get my BMR which makes me nervous because I don't want to under-eat if that will make things worse. Does anyone have any advice or support, I'd really appreciate it

So you were eating at X and lost some.
Went on vacation and ate at Y and did not gain or lose. (bummer you didn't log - that would have been your TDEE to take a deficit from - well, for that level of activity anyway).

Now you have been eating at X - 100 to 200, plus exercise calories, and maintaining.

So you have seen that eating less still resulted in equilibrium and no loss. Sure you want to keep going that direction?

The weight loss goal YOU selected has resulted in the daily goal being about estimated BMR - the amount of calories your body would like to burn just sleeping all day.
But you don't sleep all day, you have very active workout routine plus normal daily life.

Exercise calories for eating back are determined by what exactly?
And for what types of workouts?

Unless you are lifting heavy 3 x week or more and eating lots of protein, you are not adding on muscle, but if doing cardio you can be adding on glucose/water stores for that effort. But that will stop after about 3lbs max. Though if you weigh at the wrong time you can see bad false weight gain/loss.

The fact you have to stuff yourself probably just means stomach has shrunk. Possibly metabolism is slowing down.
One good, one not.

Just remember, you feeling full is very different and has no bearing on your body being fed fully for the level of activity you put it through.

Your BMI is already around 17 which is underweight. If you are 6 feet 5.5 inches tall you probably should be eating more calories than BMR. I'm no expert but you probably look pretty hot if not a little on the thin side right now. I wouldn't focus on weight but on the muscle tone and shape of your body. Curves are kick'in!

Lots of questions, so here's a bit more info.

I am 22, I am 6'5.5'' and weigh 146.6 pounds, and I'd like to weigh (ideally) 125 though I could settle for 130.

I have set MFP to lose 1 pound a week.

I've been trying to lose weight for three years. I started weight-lifting then two or three times a week, so I can't imagine I'm building much more muscle weight. I have lost 15 from my heaviest weight three years ago and completely changed my lifestyle (I became gluten free and eat fruits and vegetables everyday which I refused to touch three years ago).

This last year has been pretty static which was why I joined MFP. I wanted to be more mindful with the quantity I put in my body since I had already changed the quality.

I calculated my BMR and TDEE from one of those newbie threads I read on here, which said my TDEE was 2316, which would put a 20% loss at 1853. However, MFP sets me up around 1410, which is about my BMR.

I think that is all the relevant information. Does that mean I should be eating more? How can eating more help me lose?

65", or 6'5"? Big difference in BMR there, 150, which makes TDEE estimate even bigger difference. Sounds like you used 65" though.

So 20% deficit is appropriate now for amount to lose, but it soon won't be.

How can eating more help lose? It's eating more than an extreme deficit for your level of activity would give you, but still less than what would maintain.
Vast majority have no idea what maintain calories would actually be, purely estimates.
But if you start on the low side, especially with exercise, you can slow your metabolism down, and weight loss slows down and may stop.
But if start on the high side, especially with exercise, you get benefits from exercise, and while weight loss may be slow, body measurements improve, and you can always cut out a few more calories from this direction and be alright.

Now, if you at MFP's suggested 1410 and correctly ate back exercise calories like it's intended to work, would you be above 1850 anyway, on exercise days? Or more?

Because you did select wiser goal than many start out with at least, good job. You could keep doing it the MFP way, and log all exercise, and eat back all of those calories, and you'd get the same results.

Or go the manual method, manually set 1850 which includes exercise, don't eat exercise back, so if you log it do it as 1 calorie or after you met daily goal.

For logging your stats for changing them as weight changes, try the spreadsheet.

http://www.myfitnesspal.com/topics/show/717858-spreadsheet-bmr-tdee-and-deficit-calcs-macros-hrm