Struggles

So I will admit, I constantly struggling with feeling if I'm good enough. Especially in my relationship. My boyfriend is absolutely amazing, he is always there for me and everything. He always shows me I'm perfect for him, how I am enough for him. But I struggle because there is always someone better, more in shape, someone that doesn't look like a lumpy potato like me lmao. I am just so afraid. I haven't dated a lot of guys, but every guy that I've dated has cheated on me, with the exception of my current boyfriend. All that made me feel more and more like I wasn't enough. I know I'm not the only person that struggles with this, but does anyone have advice? How do you girls deal with this? I need advice on how to have better self esteem and how to hold myself at the level of respect that I should be at.