Weight loss.

I’ve always been funny with food, either eating to little or to much. My weight has doubled in 4 & 1/2 years (I think it’s because I got into a relationship and we are very happy) I’m finding it super hard to lose weight living with someone that is very outgoing and puts weight on in a good way. I need advice please?! I’m desperate to lose weight, I’ve tried tablets, crash diets, slimming world. I’m currently attending yoga classes and PT sessions, but I feel like I’m not getting anywhere. Do you go from the scales or the way your clothes fit? I’m starting to give up, I just want to be healthy and happy. How long will it be until I see results? How do I resist temptation? I’m under a lot of stress from university so I think that is a contributing factor to the overeating too. I’d be really grateful to hear your thoughts.