Question for nutrition/fitness experts who are very familiar

Yellowstone1983

So I have less than 2 weeks to go with my first round of Insanity... I am 5'2", 28, and started the program at 149 pounds.. I used the formula to calculate my caloric needs, which were 2,400 to maintain and 1,900 to lose. I was eating between 1,400 and 1,800 daily, usually closer to 1,800 and when I started the second month I really started to plateau at 140 (for over 2 weeks) so I got discouraged and had about 4 days of "reckless abandon" eating 2,400 calories a day and somehow managed to finally break out of the 140s hitting 139.0 .. Well I also decided to recalculate my caloric needs now that I lost 10 pounds: 2100 to maintain and 1600 to lose... A difference of 300 calories for 10 pounds seems like a big number.. And it's no problem for me to adjust, but I just really don't want to get stuck in my weight loss again and based on breaking my last plateau it seems like I may not have been eating enough in the first place... Any advice to help me keep losing fat?