You are on the right track with attitude. You dont need your parents to find out, thats fine, I understand.
The one thing that will help you more than dieticians and anyone else- is yourself. Losing weight is such a mental commitment thing combined with snesible choices. Eg My wife and I went to a nearby city this morning and had lunch. We mentioned Hungry Jacks then my wife said "Subway for me". I knew she was right. She had teriyaki chicken and salad and I had a 6 inch grain roll with ham and salad. Far better than a burger.
If you eat sensibly and dont lose weight, dont worry, it will take time ...at least you are eating healthy. If other people dish up food that isnt good for you then peel off the pastry or leave the fried food or refuse the sweets. Better not to be fanatical about it- sensible and measured.
Your intention should be to get food and eating habits off your mind so you can enjoy life. Life involves food and eating but we dont eat and enjoy food to live.
We like shopping for no sugar foods. No sugar cake, no sugar chocolate, flavoured porridge is great, low carb bars. It wont be easy while living at home as these foods cost more but you can plan your future food intakes.
A famous person once said
"you are what you eat" So eat sensible but also accept yourself for who you are. We can all be model figures.