Constantly hungry even after eating

Well, being smaller you DO need fewer calories than you did when you were larger, but there are some work arounds. How fast are you set to lose? If you're still at 2# per week, you can go in and lower that which will give you more calories for the day. Actually, at only 15# left to lose, you SHOULD do this- a healthy rate at this point is 1/2# per week.

Also, are you drinking your water?

At what point do you know if you are genuinely not eating enough for your new weight? Or am I smaller now so don't need as many calories?

You'll continue to loose weight and be lethargic if you don't eat enough for your new weight.

More protein/fat and less carbs may help make you feel full at the same calories.

Agree that you are definitely not getting in enough protein! I went back quite a ways in your diary and saw a range from 29g to 59g a day - not one single day when you even MET the goal. MFP's protein goal is absurdly low to begin with, at a mere 15% of daily calories from protein, and you aren't even meeting that. No wonder you're still hungry all the time!!

As a comparison - my protein goal is 179g per day and I nearly always meet it (if not go over!!). I plan my eating around my protein goal, it's the first macro I ENSURE that I meet, followed by fat (enough dietary fat also helps with feeling satiated), and then carbs fill up the rest. I will note that I am a bit taller than you (5'8") and still heavier (CW 177), but that's not going to make all that much of a difference in where your protein target should be (fwiw mine is set at 35% of my calorie intake bc that's as close as I could get it to the # that IIFYM.com gave me. Even if you stay with 1200 as your calorie goal, 35% is a *%#*-ton more than you're currently getting). Bump your protein, a LOT, it will help dramatically.

i think everyone already hit the nail on the head.

Drink LOTS of water. Half you weight in OZ of water daily, and more if you are working out and sweating your tushie off.

YOU MUST, must must must eat your "banked" calories from a work out.

I know it's sounds really stupid, but you need to eat to lose. If you are working out you need to Fuel your body to do its thing.

if you do a 3 mile walk, boom thats 300 calories you can now eat! (which is basically like 2 eggs with a 1/4 cup of cheese on top and some spinach yummmmy right?)

If its the middle of the day and you just ate lunch or had a snack and your stomach is stll grumbing drink a full glass of water.

Also drinking 2 glasses of water (16 oz which is a normal "glass" that most people already have in their kitchens) before each meal. I do this and it helps me not eat as much.

Definitely increase your calories a little bit and put more protein and carbs in there. I increased mine from 1200 up to 1450 and I'm still losing and I'm not hungry all the time

If you're walking less than around four miles an hour, a 3 mile walk is around this many net calories burned:

0.3 X 3 miles X 137 lbs = 123 net calories

Greater speed I'm not sure but personally do not think it would be triple, either

I also immediately thought of an ulcer, especially since you get this pain after eating. Try seeing which foods make the pain worse, or if it is all foods, and if there is any foodstuff which calms the pain - yoghurt, for instance. See your doctor. Good luck!

I am your exact height and weight, and I'm eating ~1500 to lose .5 pound a week. 1200 calories is very low and since you are already within the healthy weight range for your height, you should be aiming to lose about .5 pound a week. Set your goal on MFP to lose .5 pound a week (or even .7 pounds a week) and see how many calories it gives you then. You're hungry because you're eating too little. I'd be constantly hungry at 1200 cal/day, too.

I also second everyone's suggestion to eat more protein (lean meats, beans, cheese, eggs, milk, etc.) and drink more water.