OP, I think the major factor in this is that you are a smaller height. Like you, I struggle to lose weight and if I could afford this i would too, BMI isnt an accurate measure of health, especially people at the fringes of height ranges or other factors. I also started gaining weight due to early perimenopause that health providers refuse to recognise, so why wouldn't I go elsewhere?
You've already said you are still in a healthy weight range for your height and are taking supplements, even when not eating you are taking protein shakes. I have no idea why some of these people are having a go 🤷🏻♀️.
Wean yourself off them now that you're happy ish with your body, keep up the exercise and keep your portions down.
Best of luck to you 😊