Why is it taking so long?

How much are you eating? What is "so long"?

Compared to previous months, has your exercise volume increased? If so, most of the weight gain is from increased water and glycogen stores to aid in repairing of tissues stressed from exercise.

Did you weigh and log all food intake before cutting calories to see how much you were eating? At your age, weight and activity level, your estimated TDEE could be as high as 2400 calories to maintain present weight. With about 40 lbs to lose, a deficit of 500 calories below actual maintenance would be more suitable. Taking into account that sometimes TDEE estimates can be over, you could likely lose approximately 1 lb per week by eating between 1700 to 1900 once your body gets used to your exercise volume and intensity. Then as you continue to lose fat and get closer to your goal, you will periodically increase calories eaten until you're 250 calories or so below maintenance with the last 10 or so lbs.

I'm 5'11 and 187 pounds. I have an hourglass figure, and a more "built" body (has more muscle/wider build than an average woman). I either bike 10 miles or run 1-2 miles every-other day. Also, I do mini workouts throughout the day, such as doing squats, 40+ sit-ups, and walking. I've been eating healthy for the past month, and exercising, but I'm still the same weight. I've lose a pant size ( used to be a 16 and 14, now im a 12), and I can fit into some Mediums. Why am I not losing pounds of the scale? Could I be gaining muscle? I want to lose a few more pounds/inches before October 25th, and I need help!

The numbers on the scale don't count. The gift is that you have went from a size 16 to a size 12 and you can fit into some mediums.

Chances are that you are not eating at a calorie deficit. In fact, it sounds like you are eating enough calories to maintain. Have you set up your fitness profile in MFP? Are you logging all foods and exercises accurately?