from the way you describe yourself and the confidence you hold in your physical appearance and personality, i would expect you to be a very sought after girl.
my only explanation for the somewhat lack of interest in you would be that you want something serious but most others simply don't at this stage.
let's be honest, many guys at uni (even girls too) are just wanting a bit of casual fun and aren't gonna bother putting effort in to chasing somebody who wants something more serious like yourself
it's an odd truth that many university relationships actually develop between people who were originally ONSs or FWBs - people don't begin looking for something serious, but then a deeper attraction develops and a relationship forms.
with respect, your problem seems to be that you're too picky.
perhaps you have a right to be picky - you know that you'd be a good girlfriend and you don't want to settle with just anybody.
the issue you have is that you've had a (presumably) serious relationship already; it made you feel comfortable and secure - you wish to find it again but you want to find it instantly.
this kind of thing isn't an instant and rapid process.
sometimes you meet somebody and "click" instantaneously, however very often attraction is something that develops gradually.
my only advice (if you could even call it that) would to be a little more open and less restrictive.
if a guy asks you out and he isn't half bad, at least give him a chance perhaps?
let him take you on one date; if there's nothing there, what's the harm?
i'm not saying give every single guy who approaches you a chance, but it would be beneficial to consider that just because you don't feel attraction to a guy now, that doesn't mean you may not find him attractive in the future if you got to know him better.