ok - proper reply now:
A few things just to think about:
1 - I would be a bit worried about viewing life as a waiting game to be happy. Your comment about not having to wait an extra year until you can finally be happy seems to me to be setting yourself up for more problems and disappointments. Life rarely ever gets easier or less stressful as you get older. Instead of waiting until some situation change makes you happy - its much more healthy to accept that life will always suck... sometimes a lot, sometimes a little, very occasionally not at all. But pretty much EVERYONE can find paths, methods, stratagies, styles etc. that let them experiance happiness and feel fullfilled dispite the suckiness of life. I have no doubt that you can do this too - and if you can find ways of making university work for you, then you don't need to wait for a circumstance change to make you happy.. you will know that no matter how *****y, you can make a go of it. True confidence does not come from easy achievements, it comes from barely scrapping through the hardest thing in your life so far, but managing to not let it beat you, and knowing that what ever comes next you can deal with it too.
2, make sure you have fully explored your universities support options.
Obviously there is the disability support services - which are normally quite good at universities. If they are not, take them to ****ign task about it and kick them in the arse until they do their job.
But there are also other ways to seek support.
For example, most universities have a chaplaincy/religious area. now, even if you are not religious yourself, these places can often be incredibly calm and supportive enviroments. When I was at university all sorts of vulnerable people went to the chaplains building and made friends with her.. not because they were christian, but because it was a clam quite supportive place, away from all the crap of university, where there was no judgement, just listening ears.
Other things you can do is talk to your university about halls.. if they were not a good enviroment last time, consider changign your circumstances. One of the best things I ever did for my mental health at university was move into post-grad halls. I never got on well with undergraduate halls, they were to crazy and messed me up a lot.. but post-grad halls were amazing. The people were much much quieter, more mature, more focused on their work and their studies.. and more supportive (if only because they were drunk far less of the time.)
Aside from this there may be student groups, and never underestimate academic support - often your lecturer/tutor may seem unaproachable, but can end up being wonderfully supportive.
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Now, for your specific circumstances, honestly I would actually say to stay. and not defer. BUT, also not commute. go back into some more suitable halls/accomodation that is better for your wellbeing.
Why? Because the key thing you said was that honestly, there may not be a great deal of change in your mental needs in less then a year.. and actually being at home and feeling like a failure can do more harm then good.
Its the oposite of what I did - but for me there was a specific cause and triggers that were present in the enviroment I was in at university.. removing myself from them for half a year, and putting myself back in later worked well. But I would say that's because my problems are much more circumstantial then your seem, your seem like something you have to deal with continuously, not only on the occasions when some specific thing happens.
I would suggest that you stick with it for now but aproach it in a very logical way. Talk to your parents, and as many people at your university as possible. Their entire job is to help you - and they will, even if it sometimes takes a bit of pushing.
See if you can find a better solution to accomodation.
See if they can push you up the priority order for extra help/support
Make sure all of your academic staff know that you may miss lectures etc,
Make sure there are no secrets and see if there are things your parents can do to help (for example either visiting you, or maybe you going back on weekends, or once every two weekends)
Make sure you have explored all of the support avenues that your university, and students union, and everything has to offer.
-- The only reason to defer is if you think your mental well being situation will improve with time at home. If so definitely do it, but if you think that next year you will face the same problems that you face now - then its best to just try and solve them now, rather then waiting a year to face the same problems.