Cupcake, if I am wrong correct me, or is it the fear of putting on any weight that stops you eating enough at the moment- what is your current BMI? (Just want to check its healthy). If your body is too underweight it wont really work properly and you will also feel under par.
Try to work out how many calories you need per day, there are stickies on the forum and also a website called fitday.com and no doubt there are countless other sites. If your finding it a real struggle its maybe worth checking to see if your able to see a dietition- it can make all the difference to sit down with someone and go through your diet and make plans with someone else who will work with you on your problem- a problem shared is a problem halved.
I'd say below 1200kcals is still too low. I don't know your height or weight or age or what you do in a day so cannot comment either way but basicly your body will get used to whatever you throw at it. If you eat too little it will try its hardest to make this work to maintain your weight, if it feels you are underweight or not eating enough to maintain your weight or even not getting the right nourishment it will send out strng cravings for more food and particulary high calorie foods as it knows it doesn't need to eat alot of these to get what it needs. Basicly make very sure your getting enough protein, enough vitamins and minerals and more importantly enough calories to maintain a healthy weight or if you are overweight (I doubt it) to get to a healthy weight.
Maybe have a plan to add in a little each week or few days to get your calories back to a norm. yes you may gain some weight, but lets face it, you say your gaining weight already. There are important hormonal changes to consider, in your 20s you will go through alot and as you age will continue to go through a few more. The main ones being about turning from a young girl (19) to a child bearing women (25) and your body trying to fix itself up to do so. As you get older, the hormones change again and another thing to consider is your bones. Calcuim is being stored in your bones until your about 30, this will help keep osteoperosis away. Once you hit 30 your bones are in decline (which does impact on your weight) but other hormones add to build muscle (again influences your weight) its all quite complex and I don't want to speak as an expert when I am not- this is stuff I have read/been told by experts and I am sure theres more written about it on Wiki.
Listen, try to get back a healthy diet, its in your interest to do so, if your worried about your weight remember that you may just find your body is trying to get you to a natural weight range which is healthier to you. Please give it a good try, a few months of eating properly, wait for things to settle regarding your weight, they may hop around a bit and remember that not all weight gain is bad, your bones, your muscles, water (which gets stored), nutrients.... its all stuff you need to exist and function properly- things will need tome to settle and I promise they will. If it all goes pear shaped you can always revert back to what your doing now, which is ill advised but if thats what you really want...
looking for some help 
