TDEE, BMR, Im confused and need help!

Hey there everyone.. So I am trying to loose the last 20 pounds to get to my goal, I could probably stand to loose more than 20 but I think I will be happy with that, we shall see. I am trying to stick to a 1200/day calorie intake, and exercising for 60 minutes, 4 days/week. So far I have lost 33 pounds, but I am stuck at this current weight. I just read that a 1200/day cal diet is unhealthy and to eat more!?! The article said to go by my TDEE and take 20% off that to get my daily calorie intake.. How do I get my TDEE and how do I use it to loose more weight? Any advice will help.. thanks!