I haven’t read all the comments but it seems to me you are focussing on the wrong thing to start with. You are putting pressure on yourself to lose weight for your wedding - I get that, it is an understandable thing to want to do. The trouble is that your focus sounds like (I can only go on what you say here so could be completely wrong) it is on the short-term “fix” of losing some weight rather than on the long-term goal of getting your health sorted out.
The fact that you have been on many diets before and they don’t work will tell you something about calorie restriction. The trouble is, you are focusing now on a calorie deficit. Your body is holding on to weight for a reason and you need to find out why. I don’t think that cutting this, that and something else is going to do the trick. It is quite possible that you are not eating enough - it is difficult to tell from what I have read here. How were you eating before? It sounds like you were quite probably on a healthy plan before, just higher carb?
I think you need to look inside to see what is going on. I would want to know what the following health markers had to say - so blood tests.
- thyroid (TSH, Free T3, FreeT4 and antibodies)
- iron panel (inc ferritin, saturation, folate)
- B12 and ideally other Bs
- vitamin D
- HbA1c
- fasting insulin
You say you get plenty of sleep - good quality sleep? How are your stress levels? What health issues have you had in the past? What is your weight gain/loss history? You say you have always struggled with weight - since childhood or more recently?
There are so many factors that can influence your weight. What is important is getting to the root issues of your health. If you heal them, your weight will stabilise to where it needs to be. IMO the better focus would be long-term health and happiness and the weight will naturally follow. I know that isn’t what you want to hear because of the wedding target. I think that getting a proper handle on what is going on will be a great place to start and hopefully give you some answers so that you can be a bit kinder to yourself and enjoy your special day in a body well on its way to finding its perfect balance. Different people lose different amounts in different patterns - there simply is no standard weight loss pattern to be expected and anyone who tells you different is misleading you. It is actually very typical for women to have no weight loss for quite a while. I have seen many gain initially too. That is why it is important to focus on everything else but weight as indicators of whether this is the right way of eating for you or not. You could quite easily have a hormonal issue that is putting the brakes on, inflammation, auto-immune issues.