Take a breath.
This is a long haul, lifestyle.
There is no "one" diet fits all. It does not work that way.
Don't look at this as a drudgery or torture, but a challenge to learn!
The first thing you need to learn is about yourself.
Track everything. Food, fitness, sleep, work schedule, family, what ever.
Track/journal the good, the bad and the ugly. Then use the information, that gives you, to figure out how to move forward.
I have been doing the lose/gain thing since I was 15. I am now 56. I did not figure this out until the last 10 years. I even slipped there. The last 5, finally success. Because, I quit looking at it as torture and starvation, and embraced, exploring healthy, tasty food, and fitness thing, I like to do!