advice please - if possible.

I had two surgeries on my body in the period of 1 year and this basically lead to my weight increasing. Currently I am 198 pounds, 26 years old, and male. My diet since my surgeries has been very low - like for instance daily i would eat like maybe 600 calories a day With some exercise. I am used to fasting so this didn't really effect me. My sister found out and she told me that i should be eating 2100 calories... Well anyways my weight isn't changing - for four days now i have been using an app which basically records the foods that i eat and the exercises that i do. I have been maintaining a calorie intake of 2000 calories + exercise.

What can i do to shred weight? I have changed my eating habits and i go to the gym. I have plenty of time on my hands - just tell me what i need to do please. I keep thinking of my previous body and i keep looking at myself now and is slowly killing my confidence. The way i run, move, and basically everything has changed and it so annoying :(

Help.

Thanks.