Most Helpful Girl
The sexiest thing a man can do is dress well.
Personally, I prefer classy-looking men. The way you're dressing now fits that description, and it seems fine to me. But you're looking for advice, and that's what I'll give you.
Try mixing in different ties and shirts. A red tie looks smashing with a black shirt, and a black tie looks good with nearly any colour. Try vests, too. One black pinstripe vest will go very far in a wardrobe like yours, as it is very basic, and it looks great. If you're feeling really casual, try button-up shirts with an "edgier" style; you can find ones with skulls or zippers or anything at all, and plenty of stores carry them. They're perfectly acceptable in a college setting (insofar as your peers are concerned). Pair them with dark wash jeans (with no rips, please and thank you) that fit you well. A nice dark wash jean is much more sophisticated than other jean colours. Just make sure that they aren't baggy.
In the end, what you wear is your decision, and it isn't really anyone else's business. Don't let other people make you feel badly because you dress the way you do. If they criticize you, then just shrug it off as politely as you can; at least you'd have the manners they clearly lack. Just be yourself, and wear what you want to wear.
I hope this helps!