It seems like your biggest problem is a co-worker that is bullying/harassing you. A co-worker, whom you have perviously complained about and has been spoken to/reprimanded/counseled (whatever your office calls it), hopefully with some documentation. In all honesty, the other issues, not liking some other co-workers and having some days that are quite busy, are things I have experienced most places I have worked.
Even if you don't have FIRE money (I'll let others debate that), you do have some FU money. Use it and stand up for yourself. If you feel you can do it confront the co-worker directly. I would tell them in no uncertain terms to stop the behavior and remind them they have already been spoken to once by management. If it doesn't stop, go back to management and/or HR and be clear, that you are being harassed and it makes you uncomfortable at work, be as specific as possible; don't say "I still don't like the way Jim is talking to me", say something like "Jim continues to harass me by making negative/unwelcome comments regarding me in X regard and this makes me feel unwelcome and uncomfortable at work." Give specifics if you can. HR, should take it seriously, especially since you may well be protected by state or federal laws regarding workplace harassment (and they may also face liability). If they don't take it seriously well, then it isn't a place I would want to work anyways. At that point you could walk away or retain an employment lawyer.
A note, I have seen people who complain (even up to sue) treated very differently by co-workers. One person who complained about behavior, lost a bunch of work-friends and that majority of people no longer interacted on with them on anything other than professional matters and even then as little as possible and often by email; obviously they were viewed as being in the wrong. While another time a co-worker complained (actually sue management and won) had a great relationship with all of their co-workers, aside from management who still treated her politely (as they had been sued, lost, and had no appetite to be seen as retaliating, again).
As a counter-point, I have had co-workers who have had issues with either co-workers or management, they all fought or soldiered on for a time and then one day they realized they were done. One quite without a new job lined up, one found a new job, and one reassessed their finances and retired slightly-early. All seeming much happier immediately after making the decision (and the longer term as well). I respect all of them for being able to assess and decide that it was not worth it, put it aside, walk away, and seemingly not think of it again.
I guess what I am saying is, if you want to fight then fight; it could get better or you could still want to leave. If you want to leave, put it all behind you and leave; you can try FIRE and if it/the math doesn't work you can always go back into the workforce or pick up a little work to makeup the difference.
As a disclaimer, I can be a little hot headed and with FU/FIRE money would love to stick it to a co-worker that was harassing me; after all I don't need the job and it is likely that they do. But, I would also be aware that it could make my workplace just as uncomfortable or even more so afterwards.
Sorry for rambling, but perhaps you can pick something of value out of it.
