Losing weight on a crunch

It's hard to be able to give you any concrete advice without knowing much about you (age, current weight, etc), but generally speaking its recommended that you can't lose more than 1% of your body weight in a week. You have about 6 weeks+ until your target date so that would be an extreme goal (unless you are starting from a very high weight which from your profile pic seems unlikely).

You could try to set MFP goal to a 2 lb per week rate of loss and try to follow that but it might mean eating under the daily recommended calories for a human being, keep that in mind.

MFP is generally set up for tracking your calories so you can make life long changes for a healthy weight, not crash course "diets", so this may not be the best tool for you.

Good luck with your journey though!

Yeah, maybe - that's very extreme, probably not health promoting, quite possibly not appearance-enhancing. Two pounds a week might be possible, but if you're under 250 pounds, you're heading into a loss-rate range where 6 weeks out is often about the time hair starts thinning from sub-par nourishment, and a vivacious, healthy appearance can be turning to a dull, listless, haggard one. Is that certain to happen? No. But it's a risk.

Losing 15 pounds in around 6 weeks means losing about 2.5 pounds a week, which means eating on average 1250 fewer calories daily than you burn. You look fairly young, but I don't know anything about your height, weight or activity level. An average sized woman at age 25 might be expected to burn 2000 calories a day if somewhat active, maybe 2200 if more active. So, if you're in that ballpark, we'd be talking about eating 750 to 950 calories daily on average.

I don't know how you eat, but just as an example of the idea I'm talking about, a Big Mac is 563 calories. Add a large Coke for maybe 360 calories, and there you'd be at 923 calories already. Yes, there are more nutrient-dense and filling choices than those, but it's still maybe a couple of thin-spread peanut butter sandwiches on whole grain bread plus an apple. The best option would probably be to cut it back to something like 3-4 servings of chicken breast (around 128 calories per modest serving, no skin, not crispy) and quite a heap of broccoli (31 calories per cup, without butter/oil or similar), maybe a glass of skim milk and some nonfat, no-sugar yogurt. Throughout, each of those examples would be all the food for the day. I'd have trouble keeping that up for 6 weeks, but maybe you can.

Instead, I'd suggest a moderate calorie cut, something realistic; maybe some appearance focused added exercise (not to lose faster, but to look more attractive); and focusing on finding some confidence building outfits.

Your boyfriend loves you the way you are. I would hope you could find confidence in yourself with something a little less difficult or radical, honestly.

Look after your health.
Your looks will follow.
The opposite is not always true.