Exactly what Blicca said.
You maybe need to remember that a "diet" can sometimes come with subconscious barriers. For years we have been fed the idea that we can lose 2-10lbs a week on a specific "diet", what we all now call fad diets. But the thing is, you want to lose weight for your health, so no fad diet will be sustainable for you, the way that you want it. You need to basically take on a whole new look at healthy eating. When you take this approach (which is quite slow), you basically embark on a learning journey, of loss and maintenance.
Like Blicca mentioned, most people will track their food on My Fitness Pal or similar style app. I spent a week looking at how I ate, learning to be honest with myself about exactly what food and drink went in my mouth. I decided not to take judgement on the first week, then at the end, look at how I could of made better choices, then started again. I originally aimed to get under 1800 calories, which took a few weeks. Once I did that, I started to drink more water, eat fresher veggies (or frozen options), more meat, more eggs, less starchy foods (pasta, potatoes, rice) less fatty foods (cheese, fried anything, candies). It took me a full year to really learn and understand my body through diet alone. Now I am 44lbs lighter 1 year in, and I never went to the gym once.
This year Is all about the gym, I started to plateau a bit towards the end, I was eating 1350 calories, and I new I shouldnt go under that, so My body was telling me that it was time to get my butt moving. I bought a Fitbit for my xmas, I aimed to hit 8,000 steps everyday (now I hit 10,000 most days, just a month in), I now attend the gym 3 times a week and have upped my calories to 1500 as I burn about 1400 on the days I am at the gym. I can't wait to see the results a few months down the line.
Take on this project, take notes, learn and just embrace everything!
While many people dont get counting calories, it is the quickest way to learn. Then once you reach your goal weight! you will know how to maintain it and never see that weight gain again!
I hope you succeed