I feel like giving up on losing weight :(?

I've been training for maybe 3 years or so and I've gain and lost. I've done so much research and tried to figure out how it works and nothing ever happens. I've gained 10kg then I've lost 5kg now. I'm trying to eat healthy and try to not make my body fall into starvation mode by eating meals throughout the day. I've been on supplements for fat-burning and it's helped a lot but now I'm starting to plateau again. Off supplements now and giving my body a break. I do a mixture of cardio and weights.
I just don't know what to do anymore! Had something that was working for a while but now nothing is working! I don't know what I'm doing wrong and I'm frustrated.
I feel like giving up on losing weight :(?
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