Weight gain 😔

Da
So I've always struggled with weight gain as it just doesn't sit well with me and I get very upset about it, but...
I had the implant fitted nearly a year ago and I don't know if its that or just me but I went from a size 8 to a 12.
I know that doesn't seem bad but I'm really upset with it, I'm covered in stretchmarks and I just feel generally bad 😔
I was teeny before and now I just feel so big compared to how I was and I was wondering if any of you ladies had any diet plans or tips to help me get back where I was before.