I know it has been a year since this was originally posted, but it just popped up on SmartPak forum today. I hope things are going a lot better for you by now, but I would like to offer some help. Every new horse is a bit scary at first because you don’t have a bond and you don’t know whether you can trust them to stop when you ask. The safest and smartest thing to do with a new horse is to work on your transitions up and down. Start at the walk halt transitions. Go 5 to 10 steps and then ask for a halt. Don[‘t just use your reins, but sit deeper in the saddle and tighten you lower back a bit to give some resistance for your horse to feel and react to. Also say “Whoa” out loud to let your horse know exactly what you want, and do small squeezes with your hands on the reins to go with your seat tightening to tell your horse you expect it to stop. If the horse doesn’t stop, then sit even deeper in the saddle and squeeze even harder on the reins. Do this at walk until you are comfortable and then once you are good at it then move up to walk to trot and trot to walk transitions until your horse understands and you feel safe. Then and only move up to cantering. Good luck.