Hello OP. I've lost 8kg over the last two years, which I know sounds slow, but it has stayed off, and that's what counts (I'd spent years losing and gaining the same 2kg). I have perhaps another 2kg to go, and I"m happy for that to be slow as well.
The big change for me was stopping drinking. I mean no booze, not the occasional glass, or Fridays only. None. It changes your metabolism. Your body can now deal with the calories from your food, it's not having to deal with the alcohol, and that MacGuffins around your mid-section (belly fat, which in women helpfully distributes itself from underarm to thigh) disappears more quickly.
Next, I changed my eating patterns to 16-8, or as close as I can get it. So you do all your eating between 11 and 7, or 12 and 8, or 10 and 6 - whatever you can make work for you. If you can exercise during the morning, while fasting, that will help burn fat. Some people find front-loading their carbohydrate intake at the beginning of their 'eating day' helps, but don't make a rod for your own back with lots of rules.
Those two changes were small, but sustainable, and helped me make all the other small and sustainable changes - drink more water, eat more veg and protein, less sugar and pasta, exercise more.
Using MyFitnessPal to track intake and weight was also helpful - I don't do it all the time now, but I do still record my weight from time to time. It's helpful to see the downward trend over time, and not get too demoralised if you're half a kilo up one week.
But if you ARE half a kilo up one week, make sure you adjust. I find a scoop of ice cream with a dollop of creme fraiche to be a weakness - fine twice a week, not good daily. So I've cut it out, because it was becoming a daily thing.
You and I (and most adult women, tbh) have had enough experience of self-monitoring around food to know what a good week's intake looks like, compared with overdoing it. You will know when your portion sizes are creeping up, or when the one slice of cake for someone's birthday is becoming a daily thing. People in offices always seem to eat a ton of sugary stuff - swerve it.
Joe Wicks said a wise thing; 'don't let a bad day turn into a bad week'. Just because you 'fall off the wagon' one day, doesn't mean you have to chuck it all away.
Start a thread on Mumsnet! Gather some friends around you on a forum and exchange news and tips with them.
You are doing something really nice for yourself, so feel proud of that.