Firstly, have you considdered going part time with your course? I'm just finishing the final corrections for a doctorate at the moment, and after I crashed in 2007, found I couldn't work whatever the heck I did due to the depression, nightmares, lack of energy and other things you describe I actually found going part time helped significantly, since it meant when I was able! to work on my thesis I could, but I didn't have to try and force myself on those occasions when I couldn't.
University is hard, and doing that on top of recovery, let alone investigations and everything else is still worse, and if it takes an extra year or so to get your degree, ---- well that's far better than not getting one at all and ending up in a bad position.
As to your feelings for this girl, well if you can perceive her interest then your doing better than me, however one thing I will say honesty is perhaps a good idea especially if you are not in a good place yourself. You don't have to be absolutely! honest, but giving part of the truth, eg, "I'd like to be closer but I'm not sure at the moment" might help a lot, especially with anxiety.
i'll also say that while you can't generalize, certainly the Spanish and portugese people I know have been very emotionally open, and often a lot less inhibited about sharing feelings than us Brits.
Before doing this however, you might want to decide what exactly you want. You say you are looking for more than a casual encounter, but not literally mariage. This is fair enough,a nd it might be love, but you might want to sort tht in your head.
I also confess I disagree with porsoft, it's quite possible to love others without loving yourself, indeed loving others is the easy part.