How do you know when you’re thin enough?

So I’m currently 5’7 and 145 lbs. i’ve been told by people around me that I’m actually getting kind of skinny. I probably would weigh a little less if I didn’t have all this extra skin as well. So I guess technically I am thin enough. I’m wearing a size 6 or 8 in pants. The thing is I’ve always had body dysmorphia, and I don’t have the ability to look at my body objectively. I still feel like I could lose more weight. I just don’t know when I should stop. I really need to get a tummy tuck so that I can get a better idea of how much of my midsection is fat and how much is just loose skin. In fact, I have loose skin all over so again it’s kind of hard to tell what is fat and what is just flabby skin. I don’t have an eating disorder or anything, and I don’t think that I’m fat in general, but I know that a lot of people who are my height are thinner than I am and not considered underweight. So how do you know when to stop?