After all the hard work you've done and all that you've endured to lose the weight, you deserve more kindness from yourself than what you're giving you.
Every man I've ever met that I've talked about the subject with has said the same thing to me: what runs through their minds when they see a partner in the altogether is never, "ew ew ew, look at those fat thighs/that saggy skin/that weirdly-shaped toe," but "OMG, I am naked
with someone! YAY!" Other people see not our flaws, but us
I've lived in a slim body and a fat body, a younger one and now a fortyish one (which still feels pretty young to me, actually). I regret that there were ever times that I let my feelings of fear or shame stop me from doing something I wanted to do. I'd have way better memories of my misspent youth now if I'd had more confidence (and not just in the bedroom).
You have a phenomenal opportunity right now, while you're in your early twenties and have freed yourself of so much weight, to let yourself be "good enough." There are a lot of different ways to reach that place of good-enough. Maybe it'll take a little therapy, maybe you can do it by yourself by taking a long look in the mirror and replacing all the self-deprecating, negative thoughts with positives, maybe it'll just take some time to get used to the major
changes your body's been through. But you definitely deserve to get there.
I second Transporter's exercise recommendation, if you aren't already weight training. Exercise in general helps you focus more on what your body can do, not just on what it looks like--and what you can do is way more important than how you look. Beautiful, but static bodies are for photoshopped magazine spreads; living ones sometimes take a weirdly unflattering angle or have extra fat or wrinkle or sag, but they are infinitely more interesting to get to know.
As for scars, they're just proof that you've lived through something traumatic long enough to heal from it. Any partner worth his salt sees a scar and is grateful that the beloved person bearing it trusted him enough to let down all defenses. It sounds a little weird, maybe, but...I like
knowing how my husband got the mars and scratches he's gotten on his way to 43. They make him unique, they make him him
I wish you luck; I think it's a problem we all struggle with at some point, no matter how gorgeous we may sometimes feel.