I feel like I am among the few on this forum that would suggest going to more "natural horsemanship" route, and begin teaching her to "send" places, and ultimately be able to send her into the trailer, like in this video:. I am a strong believer in not having to enter the trailer while loading your horse, and after teaching all three of my horses to load like this, I have yet to have them refuse loading in any trailer. I grew up having slant load trailers available, so it was truly easy to walk in with my horse, but my friend got a straight load trailer without a way to physically walk the horse in - thus the sending method comes in handy. My horse was awful at trailering for months before I taught him how to send into a trailer, and it truly has been a lifesaver many times. If you aren't confident teaching this, get a trainer, you'll thank yourself in the long run.