TDEE

I use lightly active because sometimes my schedule allows for exercise and sometimes not so much but I usually end up getting at least 1 hour a week in. This way, I do not eat back exercise calories. I like this method because you are taking SOME of the estimation out of the equation. If I don't eat back exercise calories I don't worry about if I have over or underestimated how much activity I am doing. I eat the same every day and if I had an intense work out and am hungry I will eat a little over my lightly active TDEE - 15-20%

EDIT: It really depends on if you want to record and eat back exercise cals or not. MFP is set up so you eat back all exercise cals, TDEE -20% is set up so you do not eat back exercise calories at all. Because TDEE is calculated based on everday activities and exercise you put your activity level to include exercise. On MFP any exercise is considered an extra deficit, so you are at a deficit before you exercise at all.

TDEE confuses me....In MFP, I am considered sedentary because I have a desk job even though I am working out twice a day...I went to an online website and my BMR is 1226.49 and my TDEE is 1901.06 if you are moderately active and 1471.79 if you are sedentary...So, what do you go by??? I am sedentary??? So 20% less than that would be 1177.43 if sedentary and 1520.85 if you go by moderately active...Help, please!!!

I think you got something wrong.
These numbers seem very very low. Are you sure you are calculating this correctly?

I have a hard time with anyone going for sedentary, even with a desk job. If you exercise at all (especially twice a day!), or really do anything beyond moving from your bed to your sofa and flipping channels all day, I'd say you aren't sedentary. I know some people go for that setting and plan to eat all the exercise cals back, which is good.

With two a day workouts, you're at LEAST lightly active, if not higher. I'd double check those numbers, a 1200 BMR seems super low.