It's really hard to help judge your likelihood of success given three unknown (to me) factors:
1) The details of your PICU experience and why it was such a poor fit. Six months of orientation is excellent; seventeen preceptors, not so much. I do think you need to take a good hard look at yourself and what role you, your attitude, your behavior, your skills, your judgment, and your personality played in the unsatisfactory experience because I find it hard to believe that there weren't at least a couple of excellent preceptors among the 17. A red flag is always raised for me when I hear the "unsafe" label applied by a newbie or someone who's discussing why they are leaving their first job. I'm not saying that that isn't a legitimate criticism but it is also used sometimes to deflect criticism and responsibility away from oneself onto the unit.
2) The characteristics of the ED that you might enter. I have worked in four different EDs at various levels from the tiniest, rural, critical-access facility all the way up to the academic level 1 with a dedicated level 1 peds ED attached. I'm not sure that I would describe any of them as terribly "supportive" though there were and are some very supportive people within each of them (me, included). While I am firmly of the belief that new nurses can be successful starting in the ED, it is a higher-risk proposition than most because of the pace and, occasionally, the acuity that you may be expected to handle without support. While every department has had the stated intent to support the newer nurses, that sometimes falls to the wayside as things ramp up and EMS is stacking up in a holding pattern, you have legitimate sick people waiting for hours in the WR, and you're short-staffed. Then you'll have an overwhelmed charge nurse or triage nurse directing patients to your room who are perhaps much more critical than originally thought and there you are, trying to cope.
I had a situation once with an acute GI bleed (those are among the 'scariest' patients because they can look OKish right up until they exsanguinate) who decided he wanted to leave though deemed to lack capacity, in need of multiple interventions, and a doc (legitimately) getting stressed because things weren't getting done quickly enough. I pushed back, showing him how buried I was and how hard this guy was to work with. His response (again, totally legitimate) was, "maybe you need to get some help from your colleagues." I pulled him out of the door and waved my arms across the empty pod and said, "do you see anybody who's free to come help?" He immediately understood and came in to help me out himself... while leaving his other work going undone as were my other tasks with legitimately sick patients. What made this situation difficult was that it was a gradually evolving case rather than an abrupt bleeding varices brought in code 3 hypotensive and tachycardic. Had it been the latter, I probably would have had some help when I needed it. Anybody who's spent any years in the ED has multiple stories like this. As one friend puts it, "How many times have I walked around wondering if this is the shift that ends up costing me my license?" which is, IMO, a bit overdramatic but does capture the feeling at times.
ED docs and nurses can be a pretty grizzled bunch and you'll need to pull your weight and get up to speed as quickly as you can.
When I started in the ED, with less experience than you have, I was way out of my league and I fully recognized that it could end up costing me my nursing career given the potential for catastrophic failure. I was willing to take the risk and I had the confidence that I could do it but you need to be very clear about the risk that you're taking and what you're going to do to mitigate it.
3) Your characteristics... as you can see in #1 & #2, it really does come back to you and your ability to learn and integrate and self-motivate and collaborate and investigate and...
Making the leap to the ED was the wisest choice that I could have made in retrospect but it wasn't easy and there were a number of times that it could have gone really bad but didn't due to some combination of having the right person around at the right time, some good judgment on my part, and... simple dumb luck.