Why do you think you’re a nerd on the surface? Has someone told you that?
If you figured it out (either by observing the dress of others compared to yours or their speech, etc) then you’re not as much of a nerd as you think. Nerdiness, in my opinion, is by definition, someone who doesn’t fit in. If you can see where you don’t, then you are more socially aware than you think.
How are you different? It sounds like you do not embrace this “differentness”. How would you want to be more similar to others? Dressing similarly is as easy as shopping in trendy stores where you think the salespeople are “with it” and asking them to help you put outfits together. There are plenty of places that do this. If you need suggestions, just ask. I actually once approached another parent in one of my kids classes and told her I loved the way she dresses. I asked her if she could help me choose better clothing. She was SOOOOO complimented and happy to help. I wasn’t even friends with her. She was just a nice person. Socially, verbally, you might need more guidance. Carrying on conversations can be hard when you don’t know how to do it. It also takes sensitivity to those around you and the ability to read body language to tell you who’s open to talking, how long to talk, what subjects interest people. This is something you would be best off learning in a social skills group. I highly recommend it.