Gaining instead of Losing

Unless you ate over your maintenance, it's water weight. It could be from starting a new exercise regimen, it could be from your sodium intake (very likely, as your diary is mainly frozen meals/fast food, which can be huge in sodium), it could be stress, it could be TOM if you're nearing that. Be patient, it will come off.

In the meantime, check out these links to help you out in your journey:
http://www.myfitnesspal.com/topics/show/1235566-so-you-re-new-here
http://www.myfitnesspal.com/topics/show/1080242-a-guide-to-get-you-started-on-your-path-to-sexypants
http://www.myfitnesspal.com/topics/show/1234699-logging-accurately-step-by-step-guide

Have you gained weight since September 3rd? Or just with time over all? As a female your metabolism changes with age and yo-you dieting is in no way helpful. You will always put on more weight after going off the fad diet than you did when you started. You should focus on moving more and eating less. By logging your calories and exercising you will see weight loss.

A few things to remember:

1. If you don't have a lot to lose and have always been fairly active it will take longer to reach your goal.
2. When you start building muscle the scale may actually go up but your measurements will drop as fat takes up more space than muscle.
3. Be realistic in your goals. Whatever weight you put on did suddenly appear even though it might have felt that way and it won't come off over night either.
4. Maintain your determination and resolve to continue to move forward even on days you feel you "slipped"

I think its what you are eating. You're staying within your calories but you are eating alot of fast food and not alot of fruit, vegetables, etc. Try eating more fruits and veggies (either raw or cooked healthy like steamed or something like that). Are you drinking alot of water? Are you logging everything, like sugar on cereal, condiments, etc? Soda is VERY empty calories. Do you eat fast foods for convenience, or because of your job or some other lifestyle reason?

Eat whole grains that are more filling, and protein rich but heathy foods such as eggs, lean meats, low fat dairy. These will also help you to feel fuller longer.

I find that if I cut back (not out - back) on bad carbs (sugars) and try healthy carbs (fruits), drink lots of water (not sugary drinks), it can make a difference. If you don't like straight up water, try adding cut up lemon, limes or even oranges, the little bit of flavor can make a difference.

I gained 5 lbs my first few weeks after I started exercising and eating right. Then I lost 3 of it back and then last week didn't loose any lbs but I bought one of those scales that does fat % also and found that even on the week I didn't loose any lbs I lost 1% of my body fat percentage. All that to say this: if you are eating healthy and watching portion sizes, carbs and calories, and exercising, you may gain a bit at first and then flat line before you start seeing numbers fall on a scale. You will gain muscle and muscle weighs more than fat so gaining muscle will negate any fat loss you are going to see on a scale that measures lbs only. Stay focused. Keep working it. I am sure you will see the pounds start to fall away if you stay at it.

also, I just looked at your diary that you linked to, the fast food is not helping. I would suggest cutting out all fast food. Pack yourself sensible meals if you have to eat on the go. I was told to shoot for a calorie deficit of 400-500 calories less than what I am burning. I found that I had a hard time finding low calorie healthy alternatives on a restraint menu. That is not to say that you can never eat out but choose things like salad when you have to eat fast food. No greese cooked foods like burgers and fries. Also remember, fast food portions are way more than one serving is meant to be really. I do high fiber oatmeal for breakfast, a sensible lunch and then small dinner with healthy snacks in between if I need them. Lots of fruit and veg. I created a strawberry banana smoothy I absolutely love that is REALLY healthy and I have that in place of a meal a few times a week. Let me know if you want the recipe. I am rooting for you! stay focused and you can do it.

So here is my response, take it as you may.

First, your sodium is way too high. Even the daily limits set out by MFP are too high in my opinion. Generally try to stay away from pre-packaged meals as they just are chalk full of sodium. Try to find raw food alternatives if you can. Unfortunately not everyone has the time to prepare meals, but then go real simple. It takes me about 3 minutes each morning to prepare my breakfast and about the same for my lunch. I'm not perfect, I eat pizza and have bad desert snacks, we each have our crutches, but try to have them less and less . Try to stay away from Bagels or really dense carbs.

Secondly, and this for me is just how I personally feel. Take a look at your activity levels during the day, and what time you are eating dinner vs when you are going to bed. I eat less at dinner because that is the time I normally slack and watch TV. You don't need as many calories at night if that's what you do as well. Load up on calories during your "active" period and less so on your less active periods. Try to stay away from really late night snacks right before bed.

My biggest change came because I started looking at food as fuel. I realized that my desk job and my night activity level didn't require me to eat what I was eating. Yes, I look to be eating a lot less than I should be eating, but it's working for me. I've lost 57 pounds since March of this year using this mindset(and then cheating a little with some here and there pizza and icecream).

Either way, keep it up, it's mostly a mental game.

What do u mean by eating back my exercise calories??

Your MFP goal is given to you without exercise figured in. With this method you're supposed to be eating back what you burn through exercise to bring you to your net total. You're already doing this, but beware that the burns listed on MFP are overestimated, so it's best to only eat back 50-75% of your calories burned.