Are you having trouble with the machines, cannulation, that kind of thing? It will take time, lots of time (don't expect to be as good and fast as someone who has done this for a long time!), and lots of practice. I thought I was never going to figure out recirculation (at least my evil preceptor

told me so; she also threatened me with an egg timer 'cause I couldn't keep up with her - well, she only had about 8 years experience

), but guess what, I did. Initially, what helped me a lot was flash cards with the steps written out (taken from the P&P) in my pocket.
Are you in a state where PCTs can push heparin? If so, this would make the job much easier (of course you have no control over the BON's rules). It's illegal in my state, and guess what,
most of my fellow nurses let or
made them do it anyway. This bothered me a great deal, along with the other short-cuts they took. However, I refused to sink to that level and always followed P&P; it wasn't easy - I'll admit - but I was able to look in the mirror. And I stayed there for 5 years! (I left for personal reasons).
The patients will be testing you and some play games ("You can't stick me!") However, once they get to know and trust you this will change (and some won't, but don't take it personally; they weren't very nice people before they went on dialysis and that sure didn't improve their personalities

).
Nice coworkers (and I assume your preceptor) and manager are a big plus; as for your boss being focused on the numbers, he has no choice in the matter; it comes from above. But from what I hear from other nurses, this isn't limited to dialysis...
You won't feel comfortable as a dialysis nurse for at least a year; I say, more like 2-3 years (to be able to deal with most situations that may come up). It's truly different and not for everyone; the training period is especially overwhelming, you may think I will never learn this. But you may want to give yourself more time, by 6 months or so in the field you should know if this is for you.
BTW, I won't lie to you; I'm getting ready to go back to work (PRN), but not in a clinic. The early morning hours (I'm
so not a morning person!) alone were very, very difficult for me (can you believe it, although I worked these hours - having to get up at 4:00 a.m. - I didn't really get used to them in 5 years? So I figured I never would

). However, with the experience I have I had no difficulty finding a position in a hospital inpatient dialysis unit with the unbelievable ratio of 1:1. Once you have at least a year's experience, you will have no trouble finding such a position and most who work there say it's much, much easier than clinic dialysis (I'll let you know).
I wish you the best of luck, hopefully I was able to address some of your concerns and give you encouragement. Feel free to ask more questions or PM me if you like.
Happy Thanksgiving!
DeLana