First of all, congratz. I think the biggest thing from my experience was the sim part vs IOE. Much of the sim stuff was checking boxes the FAA needs and training had watered down the course too much. I went from right seat to left on the same equipment, and that allowed them to use the "short course". I needed the long course to have felt comfortable. It was really just too much. The sim experience left me pretty demoralized and literally wanting to crawl back to the right seat and be a PFO (professional FO, ie, never upgrade). After that, IOE was awesome cause I was just doing stuff I knew how to do from the other seat. It was real world and I knew the real world. So, I guess what I'm trying to say is, if you struggle in the sim for whatever reason, don't feel bad. Don't get down on yourself. Just get it done (with repeats if necessary) and it's all downhill from there.
A good F/O looks at himself as a Capt in training. I know you've been a good F/O for a long time. You'll do fine.