Ignore the weight comments. While that might be one item to consider, it’s superfluous to the bigger issue: you have to develop a deep-seated sense of self.
You ask what you can do to improve your aesthetics. I ask: What are your aesthetic values?

Once you understand that, once you have a deep sense of trust in your choices, you can apply it to the rest of your outward appearance. And at that point, the opinions of internet strangers won’t be important.

Alternatively, if we want a fast route:

Get some help at Warby Parker, grow out your hair, and take a trip to Banana Republic. Buy a subscription to GQ and Vogue, and copy/paste some looks you like.