hi there..
does sound a bit worrying if you ask me, a few points:
- i have had symptoms post surgery, tia's, headaches etc.. [mine weren't as severe and frequent as pre0surgery though] like you mentioned - and yes, the "general" minimum recovery time for any brain surgery is 3 months, then with 'our' sort of surgery, there's the possible 6-12 months for the complete effects of the by-pass to set in.
- keeping hydrated is super important! but i also find that as much water as i can drink, extreme heat still wipes me off my feet.
- occasionally remember to take aspirin - aren't you on any blood thinners regularly? i'm pretty sure almost everyone on this board is on aspirin everyday for the rest of their life. i am also on plavix (clopidogrel) - another blood thinner, and verapamil - a cerebrovascular dilator.
i would definitely be speaking to your surgeon about your medication, i'm no doctor but i no for sure that you should be on regular blood thinning medication [maybe not forever but post-surgery for a few months at least] and if you're having a lot of headaches - the verapamil sure does help.
- it would be disturbing that you're still having the same symptoms - to the same extreme - as pre-surgery... maybe it just needs time, have you had any checkup scans to see if the bypass has avoided blocking up, checked the bloodflow etc??

an important q though is which type of surgery you had, a direct bypass should immediately reduce your symptoms - if not it needs to be checked, an INDIRECT bypass though can [and mostly likely WILL] take some months before you'll notice the difference.

anyway take care, keep drinking water, don't push yourself and see your doctor!

p.s. i'm suprised you're back at class so early, you definitely have to be aware that your memory, focus etc wont be at it's best... and distractions (classmates, heat whatever..) can often have an effect on your function so be patient with yourself and dont push it!! it's only been 5 weeks!