Struggling with Body Image and Weight Loss

I have been feeling really self conscious about my body lately. When I look in the mirror I just think I look so big and focus on everything I don't like. My arms, my stomach, my double chin, & my thighs. My bf says I'm beautiful & says things like that often but I just can't help but think that he doesn't actually think that or maybe he would like me better thinner. I struggle losing weight. I hate to exercise, like most people. I feel so uncomfortable going to a gym. I have tried losing weight in the past but always fail. I want to like how I look & feel good in my body.