1000 calories per day is a starvation diet. You are either rapidly losing weight or your numbers are wrong (or you are 6 years old).
Googling for the minimum safe calorie intake returns numbers in the 1200-1800 range, and these are for people who want to lose weight rapidly.
OP is not getting 1000 calories per day, that's just the three meals. More food is being eaten through snacks, hence the "No wonder I crave cookies and chocolate so much!"
Recently I decided to try an intermittent fasting diet. To do so, I had to figure out how much I could eat on my off/down days. I realized I didn't have a very good idea about how much calories my meals have, and as I was thinking about it, I started to get curious about my diet overall. How many calories do I get a day? How much of it is from fat? Do I get enough vitamins? Etc, etc, etc. All very basic questions, and since my meals are very regular, there was an easy way to find out!
(Note: anytime you feel curious and are about to find something out, make some predictions. I didn't, but I really wish I did, because I was very surprised by my findings.)
It took only a couple of hours, and here is the result.
If you scroll down, you can see that my usual Breakfast+Lunch+Dinner only nets about 1000 calories and gives 30% daily value of fat. No wonder I crave cookies and chocolate so much!
There are many surprising results that I got from this. And knowing that I've been eating like this for the past few years... Wow. This is the epitome of a low hanging fruit. I can't believe I didn't do this analysis earlier!
Edit: I was not trying to say that I only get 1000 calories a day. Of course I get more than that, but the rest is from cookies and post-meal sweets. I always thought I just have a sweet tooth, but the fact that I wasn't getting enough calories from my main meals can also explain this.