How to lose weight

You might want to start checking out peoples' food diaries here. That'll give you some good ideas on what you should eat. You could check mine for Mon-Fri of last week. Saturday and Sunday weren't great. Also, you should do some research on nutrient dense foods. Surely you know you need to eat lean protein, fruits and veg, and whole grains, right?
I'm not sure what you mean about having difficulty achieving the numbers. Do you mean you have trouble staying under 1200 calories or you feel that you can't eat that much?

First, congrats on what you have lost. The shakes are not going to help you to learn to eat healthy for the long run. I had a couple days that I had the same problem of not getting enough calories when I exercised - because you do need to keep your metabolism up. But, so you are off 100 calories - that's not the end of the world now and then. You do need to make sure you get your fruits, vegetables , lean proteins and whole grains.
For example - if you don't like breakfast in particular - have your shake then (does it have protein? I am not familiar).
Cut up veggies and put them in "calorie counted" baggies - so you know what you are eating. Get some delicious humas and 4 tbs gives you a nice snack to go with the probably 50 calories of vegetables. You can have a 90 calorie Fiber 1 brownie for dessert -
Greek yogurt is a great 100-130 calorie snack filled with protein and some dairy. Weigh your servings of meat out before you stick them in the freezer so you are sure to get the calories and the protein. Do you have a little digital food scale - about $15 at WalMart.
I mean - I know this isn't easy or I wouldn't be here myself - but you really do need to work on eating other than shakes. Whole nutritious foods that will be delicious once you give them a try. Someone else suggested looking at other people's food diaries -I am getting ideas there too. Good luck!!!