You have my sympathies, home working is a big adjustment and also going up to full time on top must be really hard. My current job is mainly home based and it took me a long time to get used to it, although I do like it now and not sure I'd go back to being 100% office based by choice which is not something I ever thought I'd say in the first year of this job! I can understand your desire to go to a previous job/organisation you enjoyed, but it does sound like it would be a bit of a backwards step financially and career wise... if you were able to make your peace with staying in this job say 6 months more, would that leave you in a better place to move on to another job at the same level but which suits you better? Obviously don't sacrifice your mental health as this is the most important thing. I also have a very 'laid back' boss who rarely gives any feedback (and when he does it's that vague 'everything's fine, you're doing well' kind that tells you nothing) - I've just learnt to live with it and assume if there was a problem he would tell me.
On the home working front, some things that helped me:
-In order to feel like part of a team when you are all in different places, you really have to make an effort to recreate what you lose out by not having an 'office', so for instance we have a 'team chat' thread on our work IM system where we just chit chat, ask each other about our weekends, post jokes, moan about difficult clients or boring meetings etc. Obviously we're not chatting all day but like in a regular office it helps clear your head a bit to take 2 mins for some pointless small talk every so often. You can mute or close it if you want to concentrate...
-We also have regular catch up calls (once a week) and face to face meetings (once a month) and we make time in these just for general talk as well as actual agenda items so we feel closer as a team. We also use this time to try and pin our boss down a bit more on concerns/things that need improving, because it feels nicer to work on these kind of problems as a team and to show it isn't just one person feeling that way. So long as we present solutions that we think will work as a team the boss usually goes for path of least resistance and just agrees!
-On a similar note, you mustn't feel tied to your desk. I got this at first as I was so paranoid that people would think I was skiving if I so much as went to the loo and missed a call or chat. But I came to realise that's an unrealistic expectation, in most offices you are not expected to be flat out working 100% of your time, people go for fag breaks, tea breaks, chat to to their mate breaks, browse online news breaks etc., so you should give yourself that flexibility too. If your boss is like mine nothing is further away from his way of working to be actually monitoring your response rate at all times of the day, he just wants the work done without him having to do much. So long as you are delivering, who cares if you take 10 mins to put the washing on or half an hour to watch TV? I would really recommend getting away from your desk for at least 30 mins in the day, maybe go for a nice walk, it'll help your mental health too!
Good luck, hope it works out for you.