Nino,
You really wouldn't have to use myfitnesspal forever, it would just be to see what your ballpark daily calories are right now. For instance, I flushed out my diet in a spreadsheet and figured out where my macros were at. I eat the same types of things every day, or if there is a small difference, it isn't a big deal to me. But I have a ballpark idea of what I need to eat every day.
At 115# you may only get 1200 calories a day if you metabolism is on the slower side. So you could easily overshoot that on any kind of diet if you aren't paying attention to what you are eating. Just based of what you mentioned in this thread you have:
3 bananas- 315 cals
1 large potato (you said two smaller ones, so that might be the size of one larger one)- 250 cals
1 serving of humus- 25 cals
1 serving broccoli- 50 cals
So that is 640 cals of the 1200 you may get for the day. We don't know what your baseline is right now. You could do the same thing for your other meals as well. Again, just do it once to see kind of where you are at. After that you can start to tweak things (change a banana for a lower calorie fruit), etc.
Earlier in the thread you mentioned nuts, oats, fruit for breakfast and lunch (in a smoothie sometimes), quinoa, rice, etc. I am sure that is getting your calories too high. If you want, I can put a three meal plan together here for you to hit 1200 cals. You might need more than that, and we can then bump it up. I may be able to get a veggie snack in there as well. Just let me know what kinds of foods you like, and I can throw something together in a couple of minutes. How are you with some soy products? We could get your protein up more using that.