I'm really glad to see things turning around for you. I am in a somewhat similar situation to yours online poker wise but I guess I've just been running better since I started.
I've played (and won a decent bit of money in) poker for a while now but I only started using HUD a month ago so take from what I say with a grain of salt.
1) Your 3-bet% - it's way too low - At these stakes, a lot of players don't play well vs 3bets, especially OOP
2) Your CBetting frequencies - Do you end up in a lot of multiway pots? It may explain why your CB% OTF is lower than usual - if so, you CB% if fine but avoid multiway pots OOP and 3b more (don't feel obligated to defend from blinds because of 'good price' - its usually a trap, especially for players who are less experienced post-flop)
3) Don't worry too much about your overall red-line dropping so long as its not excessive. A lot of winning 6m players are (-) red-line (go statsname and look at NL 6m crushers - most of them except maybe Bajs are (-); even LLinus redline in more recent history is about B/E or slightly (-).
I started grinding online again about a month ago. In my experience, a depreciating red-line is generally a good thing especially the lower you play (it's becomes a bit different as you move up). Achieving a decent+ wr at lower stakes generally entail (1) making good (or 'exploitative') folds vs nits/fish in certain spots - but not severely under-defending; (2) under-bluffing on certain textures + bluffing in the correct spots - e.g. trying to bluff a fish off a weak Ace on even a semi-wet board is usually very very marginal.
4) As for coping with downswings - Coming from someone who had just transitioned from playing the biggest live CG they offer in my city back to grinding online (starting at the micros and slowly moving up, even though I'm rolled for higher). It sucks, but it can always get worse - you can always run worse, in poker or otherwise. Learn from the experience - quantified results usually tells you a story - so study more, plug leaks and the resilience you build from the effort it takes to pull yourself out of the rut and discipline from the good habits you build along the way is what allows you to find the greatness within yourself.
4) Don't neglect your Uni studies in place of poker. You're only at Uni once and you'll regret it if you mess it up - you have all the time in the world for poker once you graduate - I just finished law school and I did regret not putting as much effort into my studies until the final years.
All the best